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      <title>Datum / Measurement Location Features</title>
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      <div class="title_topic2" id="xps10_pagetitle">Datum / Measurement Location Features</div>
      <hr noshade="true">
      <div class="title_division">Overview</div>
      <p class="para_division">Process Aid Location Feature is the generic name used to represent a Datum Location Feature (DLF) and a Measurement Location Feature (MLF). The data stored and interaction is the same for both feature types. However, the rules are applied independently to each type. Datum and Measurement Location Features can be created on Surfaces, Holes, Pins and Slots. The following sections describe the data for a Datum Location Feature, but can be applied for Measurement Location Features as well. The DLF and MLF are displayed in different fonts, making it possible to visually differentiate between the two.</p>
      <div class="title_division">Datum Location Feature</div>
      <p class="para_division">A Datum Location Feature (DLF) is used to specify critical areas of the assembly that need to be measured, monitored and coordinated. It is a feature set displayed as two opposite vectors on the first selected geometry. The DLF is a required input for specifying datum points and contains rules for the coordination tolerance zone, which is used to evaluate coordination. This feature is essential for providing the engineered coordination of MPAW.</p>
      <p class="para_division">The DLF is positioned using the rules, values and parameters you specify. You can generate it on faces or along curves if face geometry is not yet available, and make it associative to this creation geometry or freeze it in coordinate space.</p>
      <p class="para_division">MPAW allows you to add or remove faces/curves/edges to/from the DLF feature set that do not impact the location of the DLF but are included in the coordination checks. You can specify the cross section to be used, and enter a name for the DLF. The defaults control the list of available attributes that you can add to.</p>
      <p class="para_division">MPAW has four types of DLFs:</p>
      <ul>
         <li>
            <p class="para_item"> <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/palf.html#location_feature_palf_dlf_surf');return(false);">Surface DLF</a></p>
         </li>
         <li>
            <p class="para_item"> <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/palf.html#location_feature_palf_dlf_hsp');return(false);">Hole DLF</a></p>
         </li>
         <li>
            <p class="para_item"> <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/palf.html#location_feature_palf_dlf_hsp');return(false);">Slot DLF</a></p>
         </li>
         <li>
            <p class="para_item"> <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/palf.html#location_feature_palf_dlf_hsp');return(false);">Pin DLF</a></p>
         </li>
      </ul>
      <p class="para_division">You can insert a DLF on a surface (the default DLF type), hole, pin or slot.</p>
      <div class="title_division">Measurement Location Feature</div>
      <p class="para_division">A Measurement Location Feature is used to identify an area of a multiple part stackup that will be measured and needs to be coordinated within an assembly. It is required in order to specify  <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/papt.html');return(false);">Measurement Points</a> and contains rules for a measurement coordination zone. It is a feature set displayed as two opposite vectors on the first face selected.
      </p>
      <p class="para_division">The MLF is positioned using the rules, values and parameters you specify. You can generate it on faces or along curves if face geometry is not yet available, and make it associative to this creation geometry or freeze it in coordinate space.</p>
      <p class="para_division">MPAW allows you to add or remove faces/curves/edges to/from the MLF feature set that do not impact the location of the MLF but are included in the coordination checks. You can specify the cross section to be used, and enter a name for the MLF. The defaults control the list of available attributes that you can add to.</p>
      <p class="para_division">MPAW has four types of MLFs:</p>
      <ul>
         <li>
            <p class="para_item"> <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/palf.html#location_feature_palf_dlf_surf');return(false);">Surface MLF</a></p>
         </li>
         <li>
            <p class="para_item"> <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/palf.html#location_feature_palf_dlf_hsp');return(false);">Hole MLF</a></p>
         </li>
         <li>
            <p class="para_item"> <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/palf.html#location_feature_palf_dlf_hsp');return(false);">Slot MLF</a></p>
         </li>
         <li>
            <p class="para_item"> <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/palf.html#location_feature_palf_dlf_hsp');return(false);">Pin MLF</a></p>
         </li>
      </ul>
      <div class="title_division">Accessing</div>
      <p class="para_division">To access the Datum / Measurement Location dialog in the Insert mode, do one of the following:</p>
      <ol type="1" start="1">
         <li>
            <p class="para_item">On the MPAW toolbar, choose the Datum/Measurement Location Feature icon:  <img align="bottom" src="graphics/dlf_icon.gif" border="0">.
            </p>
         </li>
         <li>
            <p class="para_item">On the menu bar, choose Tools-&rarr;Process Aid-&rarr;Datum / Measurement Location.</p>
         </li>
      </ol>
      <p class="para_division">The Datum /Measurement Location dialog appears.</p><a name="location_feature_palf_dlf_surf"></a><div class="title_division">Surface DLF / MLF</div>
      <table border="0">
         <tr>
            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
            <td valign="bottom" align="left" width="100%">
               <div class="para_note">
                  <p class="para_note_body">The information in this section is valid for both Surface DLF and MLF. For readability the feature has been referred to as Surface DLF. All the dialogs and system reactions described below are the same for Surface MLF with the exception of the feature name and dialog title.</p>
               </div>
            </td>
         </tr>
      </table>
      <p class="para_division">A Surface DLF is created when you select a series of faces/curves and specify a cross section. A set can contain either all faces (face set) or all curves (curve set). A combination of faces and curves is not allowed in the same set. A Surface DLF's vector is determined by the surface normal and tangent at the first intersection curve's (in case of multiple intersection curves) mid param (param = 0.5 ), and snapped to the plane in case you select a face(s) as the first set. Otherwise, it is determined by the surface normal and tangent at the join curve's mid param, and snapped to the plane in case you select curve(s) as the first set. You can create a Surface DLF with a face set or curve set or a combination of both types, in any order.</p>
      <p class="para_division">The Surface DLF is located at the</p>
      <ul>
         <li>
            <p class="para_item">Join curve's mid param of all the input curves in case the first set is a curve set</p>
            <p class="para_item">OR</p>
         </li>
         <li>
            <p class="para_item">First intersection curve's mid param in case the first set is a face set.</p>
         </li>
      </ul>
      <p class="para_division">If a Surface DLF has only face sets, you can turn the maturity indicator ON. Once a Surface DLF is mature, you cannot edit the DLF to contain any curve geometry. The Surface DLF location can be edited to a different location using the Edit Location function on the Datum / Measurement Location dialog in the Edit mode. The location of the Surface DLF can be frozen using the Freeze Location function. Once the location is frozen, adding/removing geometry to/from the DLF does not affect the location.</p><a name="location_feature_palf_dlf_hsp"></a><div class="title_division">Hole/Slot/Pin DLF/MLF</div>
      <table border="0">
         <tr>
            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
            <td valign="bottom" align="left" width="100%">
               <div class="para_note">
                  <p class="para_note_body">The information in this section is valid for both Hole/Slot/Pin DLFs and MLFs. For readability the features have been referred to as DLFs. All the dialogs and system reactions described below are the same for Hole/Slot/Pin MLFs with the exception of the feature name and dialog title.</p>
               </div>
            </td>
         </tr>
      </table>
      <p class="para_division">You can create a Hole/Slot/Pin DLF by selecting a number of sets of edge/curve geometry to define a hole. A set can contain either all edges (edge set) or all curves (curve set). However, you cannot select a combination of edges and curves in the same set. The vector direction is calculated based on the axis of the hole or slot if the</p>
      <ul>
         <li>
            <p class="para_item">Selected edge is part of a solid model</p>
         </li>
         <li>
            <p class="para_item">Edge is part of a hole (inner loop of a face)</p>
         </li>
         <li>
            <p class="para_item">Hole/slot is not blind</p>
         </li>
      </ul>
      <p class="para_division">If the edge is part of a sheet, and if there is only one sheet, you must specify a vector to define the vector direction. If there are multiple sets of edges/curves, the vector is automatically calculated between the centroid of the first set geometry and second set geometry. There is no associated cross section. When you select an edge of a hole/slot which is an inner loop in a face (hole/slot located on a single face), all the other edges of the hole/slot are automatically selected.</p>
      <p class="para_division">Similarly, when you deselect an edge of a hole/slot, which is an inner loop in a face, all the edges of that set are deselected.</p>
      <p class="para_division">You can specify the vector direction using the Specify Vector Direction button if you do not want to keep the DLF at the system calculated direction. The Hole/Slot DLF is associated to the geometry used for calculating the direction of the vector. In all cases, the vector location is at the centroid of the first set geometry, except in the case of Freeze Location. While freezing the DLF location, you can specify a location of your choice. When a DLF location is frozen, the location is fixed and does not participate in a model update. Adding/removing geometry does not affect the DLF location.</p>
      <p class="para_division">When the DLF location is thawed, it is located at the centroid of the first set geometry. MPAW calculates the vector direction, if the input geometry is sufficient for the calculation. Otherwise the vector retains the direction at which it was frozen.</p>
      <div class="title_division">Dialog Help</div>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/dlf_mlf.gif"></p>
      </div>
      <div class="title_figure">Datum/Measurement Location Dialog</div>
      <table cellspacing="0" width="100%" align="center">
         <tr>
            <th bgcolor="#c0c0c0" colspan="1" rowspan="1" valign="middle">
               <p class="para_th">Item</p>
            </th>
            <th bgcolor="#c0c0c0" colspan="1" rowspan="1" valign="middle">
               <p class="para_th">Description</p>
            </th>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Process Aid Location Feature</p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Select one of the following:</p>
               <ul>
                  <li>
                     <p class="para_item">Datum Location</p>
                  </li>
                  <li>
                     <p class="para_item">Measurement Location</p>
                  </li>
               </ul>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Type</p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Select one of following DLF/MLF Types from the option menu:</p>
               <ul>
                  <li>
                     <p class="para_item">Surface</p>
                  </li>
                  <li>
                     <p class="para_item">Hole</p>
                  </li>
                  <li>
                     <p class="para_item">Slot</p>
                  </li>
                  <li>
                     <p class="para_item">Pin</p>
                  </li>
               </ul>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Face/Curve/Edge Selection</p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Use the Previous  <img align="bottom" src="graphics/dlf_dia_ar1.gif" border="0"> and Next  <img align="bottom" src="graphics/dlf_dia_ar2.gif" border="0"> arrows to specify the different sets of input faces/edges/curves. You can traverse through selected sets to select new geometry, or deselect existing geometry using the Previous arrow. Once you select a particular type of geometry (faces/curves/edges) you may select only that type of geometry for that entire set. To select a different type of geometry in any set, deselect all geometry in the set and then select the new geometry type.
               </p>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td"> <img align="bottom" src="graphics/dlf_dia_name.gif" border="0"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Enter a name for the DLF/MLF. The prefix and name should not exceed 20 alphanumeric characters.</p>
               <table border="0">
                  <tr>
                     <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
                     <td valign="bottom" align="left" width="100%">
                        <div class="para_note">
                           <p class="para_note_body">The prefix supplied by the system is controlled by the DLF/MLF Name Prefix setting in the  <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/pref.html');return(false);">Preferences-&rarr;Datum Location</a> dialog. The DLF_Name/MLF_Name is an attribute that is stored with the DLF/MLF. 
                           </p>
                        </div>
                     </td>
                  </tr>
               </table>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td"> <img align="bottom" src="graphics/dlf_dia_splane.gif" border="0"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Click to specify the cross section that the DLF/MLF should fall within. The Datum Plane dialog appears:</p>
               <p align="center"><img align="bottom" src="graphics/dlf_pl_sel.gif"></p>
               <p class="para_td">You are cued to select an existing datum plane or create a new one.</p>
               <ul>
                  <li>
                     <p class="para_item">Select an existing datum plane directly in your graphics window.</p>
                     <p class="para_item">OR</p><a name="location_feature_palf_dlf_cplane"></a><p class="para_item">Choose  <img align="bottom" src="graphics/dlf_plsel_pt.gif" border="0"> to create a new datum plane. The Plane Subfunction dialog appears. Select one of the available options and choose OK.
                     </p>
                  </li>
                  <li>
                     <p class="para_item"></p>
                  </li>
               </ul>
               <p align="center"><img align="bottom" src="graphics/dlf_pl_sel.gif"></p>
               <p class="para_td">The DLF/MLF direction vector is snapped to the selected datum plane.</p>
               <table border="0">
                  <tr>
                     <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
                     <td valign="bottom" align="left" width="100%">
                        <div class="para_note">
                           <p class="para_note_body">The Specify Section Plane button is available only for Surface DLF/MLF. </p>
                        </div>
                     </td>
                  </tr>
               </table>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td"> <img align="bottom" src="graphics/dlf_dia_sname.gif" border="0"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Enter a name for the section. The name should not exceed 30 characters. If the datum plane name exists, that datum plane is selected. Otherwise, the name is assigned to the datum plane you have selected. This field is not available for Hole, Slot and Pin DLFs/MLFs.</p>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p align="center"><img align="bottom" src="graphics/dlf_dia_inh.gif"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Click to open the Specify Relationship dialog. All the feature names of DLFs/MLFs that contain section planes are listed in single selection list box. You can select a DLF/MLF from the list or from the graphics window. This option is not available for Hole, Slot and Pin DLFs/MLFs. You can also specify the relationship.</p>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p align="center"><img align="bottom" src="graphics/dlf_dia_srel.gif"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Click to open the Specify Relationship dialog. This button is sensitive in the Insert mode only when at least one DLF/MLF already exists in the part, and is always sensitive in the Edit mode. Using the Specify Relationship dialog you can select multiple DLFs/MLFs and specify the relationship type from the option menu. You can choose from three types of relationships:</p>
               <p class="para_td"><img align="bottom" src="graphics/dlf_flush.gif" border="0"> Maintains a flush relationship among datums. MPAW makes no attempt to verify the flush condition.
               </p>
               <p class="para_td"> <img align="bottom" src="graphics/dlf_gap.gif" border="0"> Maintains a gap relationship among datums. MPAW makes no attempt to verify the gap condition.
               </p>
               <p class="para_td"> <img align="bottom" src="graphics/dlf_ns.gif" border="0"> Maintains a non-specific relationship.
               </p>
               <p class="para_td">You can break the relationship by choosing  <img align="bottom" src="graphics/dlf_nr.gif" border="0">.
               </p>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td"> <img align="bottom" src="graphics/dlf_dia_svdir.gif" border="0"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Click to open the Vector Constructor dialog. If the selected edge is part of a solid model, edge is part of a hole (inner loop of a face) and the hole/slot is not blind, MPAW calculates the vector direction based on the axis of the hole or slot.</p>
               <p class="para_td">This step is mandatory for Hole/Slot/Pin DLFs and MLFs where the direction cannot be determined. If the direction is specified, the DLF/MLF vector is inserted along the specified direction for all cases. This dialog option is not available for Surface DLF/MLF.</p>
               <p class="para_td">For help on the Vector Constructor dialog, see Gateway-&rarr;Common Tools-&rarr;Vector Constructor.</p>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">DLF/MLF Direction</p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">One of the three following toggles is automatically turned ON during creation of the DLF/MLF. MPAW analyzes the primary direction of the DLF/MLF vector and assigns the following:</p>
               <p class="para_td"><img align="bottom" src="graphics/dlf_dia_fa.gif" border="0"> if in absolute X
               </p>
               <p class="para_td"> <img align="bottom" src="graphics/dlf_dia_ud.gif" border="0"> if in absolute Y
               </p>
               <p class="para_td"> <img align="bottom" src="graphics/dlf_dia_io.gif" border="0"> if in absolute Z
               </p>
               <p class="para_td">These toggles are not available for input while the DLF/MLF is being created (in the Insert mode). When you create a DLF/MLF, MPAW automatically calculates the DLF/MLF direction and turns the respective toggle ON. You can modify the DLF/MLF direction while editing the DLF.</p>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td"> <img align="bottom" src="graphics/dlf_dia_rep.gif" border="0"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Turning this toggle ON and then clicking  <img align="bottom" src="graphics/ok.gif" border="0"> opens a dialog that you can use to reposition the DLF/MLF on the instersection curve.
               </p>
               <p class="para_td"><img align="bottom" src="graphics/dlf_rep.gif" border="0">Use the Percentage Along Curve Length scale to specify the location of the DLF/MLF along the curve. Enter the snap value and location coordinates and click OK or Apply.
               </p>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p align="center"><img align="bottom" src="graphics/dlf_dia_mat.gif"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Turn this toggle ON to assign the attribute value &quot;True&quot; to the DLF/MLF. You may want to assign this value if the datum is in a stable location and is not expected to be moved by further engineering changes. This attribute is strictly user-controlled and MPAW makes no attempt to verify the validity of this setting.</p>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p align="center"><img align="bottom" src="graphics/dlf_dia_fl.gif"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Turn this toggle ON to freeze the location of the DLF/MLF. Turn this toggle OFF to thaw the DLF/MLF location. When you freeze location while creating the DLF/MLF (in the Insert mode), the Point Constructor icon  <img align="bottom" src="graphics/dlf_ptcons_icon.gif" border="0"> appears sensitive. Clicking this icon opens the Point Constructor dialog that you can use to specify the location of the DLF/MLF before freezing.
               </p>
               <table border="0">
                  <tr>
                     <td valign="top" align="left"><img align="left" src="../graphics/warning.gif" alt="Warning" title="Warning"></td>
                     <td valign="bottom" align="left" width="100%">
                        <div class="para_warning">
                           <p class="para_warning_body">This toggle is sensitive in the Edit mode. However, the Point Constructor icon remains insensitive through all edits. </p>
                        </div>
                     </td>
                  </tr>
               </table>
               <p class="para_td">In the Edit mode, turning the Freeze Location toggle OFF &quot;thaws&quot; the DLF/MLF's location and allows it to move to reflect changes in the geometry selected for this DLF/MLF. In case of Surface DLF/MLF, the DLF/MLF is reattached to the mid-point of the first intersection curve if the first set happens to be a face set, or to the mid-point of the join curve of all the curves input in the first set. In case of Hole/Slot DLF/MLF, the DLF/MLF is reattached to the centroid of the first set curves or edges selected.</p>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td"> <img align="bottom" src="graphics/cpt_dia_nao.gif" border="0"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">This toggle appears sensitive only if the part has at least one DLF/MLF.</p>
               <p class="para_td">Turn this toggle ON to delete the intermediate features created during the process of DLF/MLF creation. Once a DLF/MLF is made non-associative it cannot become associative.</p>
               <p class="para_td">When you turn this toggle ON while creating the DLF/MLF (in the Insert mode), the Point Constructor icon  <img align="bottom" src="graphics/dlf_ptcons_icon.gif" border="0"> appears sensitive. Clicking this icon opens the Point Constructor dialog that you can use to specify the location of the DLF/MLF before making it non-associative.
               </p>
               <table border="0">
                  <tr>
                     <td valign="top" align="left"><img align="left" src="../graphics/warning.gif" alt="Warning" title="Warning"></td>
                     <td valign="bottom" align="left" width="100%">
                        <div class="para_warning">
                           <p class="para_warning_body">Once you have turned the Non-Associative toggle ON, the DLF/MLF cannot be edited. You can only modify some attributes. </p>
                        </div>
                     </td>
                  </tr>
               </table>
               <table border="0">
                  <tr>
                     <td valign="top" align="left"><img align="left" src="../graphics/warning.gif" alt="Warning" title="Warning"></td>
                     <td valign="bottom" align="left" width="100%">
                        <div class="para_warning">
                           <p class="para_warning_body"> CAUTION: This toggle is sensitive in the Edit mode. However, the Point Constructor icon remains insensitive through all edits.</p>
                        </div>
                     </td>
                  </tr>
               </table>
            </td>
         </tr>
         <tr>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td"> <img align="bottom" src="graphics/dlf_dia_ch.gif" border="0"></p>
            </td>
            <td bgcolor="#f7f7f7" colspan="1" rowspan="1" valign="top">
               <p class="para_td">Click to open the  <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/ref_dat_char.html');return(false);">Datum Characteristics</a> dialog. Using this dialog you can add attributes to the DLF or MLF. Each site controls the list of available attributes by modifying the ugdatum.dpx file found in the ugprocess_aid directory. A set of generic attributes is supplied with the module. For more details on the Characteristics dialog, see Characteristics.
               </p>
            </td>
         </tr>
      </table><br><div class="title_division">Inserting</div>
      <p class="para_division">To insert a DLF or MLF</p>
      <table border="0">
         <tr>
            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
            <td valign="bottom" align="left" width="100%">
               <div class="para_note">
                  <p class="para_note_body">Selecting the Datum Location option in the Location Feature dialog creates a DLF. Selecting the Measurement Location option in the Location Feature dialog creates an MLF.</p>
               </div>
            </td>
         </tr>
      </table>
      <table border="0">
         <tr>
            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
            <td valign="bottom" align="left" width="100%">
               <div class="para_note">
                  <p class="para_note_body">The information in this section is valid for both DLFs and MLFs. For readability we will refer to the features as DLFs. All the subsequent dialogs and system reactions described below are the same for MLFs with the exception of the feature name and dialog title.</p>
               </div>
            </td>
         </tr>
      </table>
      <p class="para_division">The DLF can be created on a surface (the default DLF type), a hole, slot or pin. When the Datum / Measurement Location dialog appears, you are cued to &quot;Select faces or curves for set #&quot;. The dialog displays values from the last invoke of the dialog.</p>
      <ol type="1" start="1">
         <li>
            <p class="para_item">Select geometry.</p>
            <p class="para_item">When you select geometry, the Previous  <img align="bottom" src="graphics/dlf_dia_ar1.gif" border="0"> and Next  <img align="bottom" src="graphics/dlf_dia_ar2.gif" border="0"> buttons become sensitive. These buttons are insensitive by default. You can add as many sets as you want by clicking the Next  <img align="bottom" src="graphics/dlf_dia_ar2.gif" border="0"> button.
            </p>
            <p class="para_item">Surface DLF: Select faces from solid/sheet bodies or select curves. Select only faces or only curves for a set. You cannot combine faces and curves in a set.</p>
            <p class="para_item">Hole/Slot DLF: Select the edge(s) of a hole or slot, or select curve(s). Select only edges or only curves for a set. You cannot combine edges and curves in a set. If you select/deselect an edge of a hole or slot that is not distributed over more than one face, all other edges are selected/deselected automatically.</p>
            <p class="para_item">Pin DLF: Explicitly select all the edges that constitute the pin. MPAW does not make automatic selections in case of Pin DLF.</p>
         </li>
         <li>
            <p class="para_item">Enter a name for the DLF.</p>
            <table border="0">
               <tr>
                  <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
                  <td valign="bottom" align="left" width="100%">
                     <div class="para_note">
                        <p class="para_note_body"> NOTE: The prefix supplied by the system is controlled by the DLF Name Prefix setting in the  <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/pref.html');return(false);">Datum Location Preferences</a> /  <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/pref.html');return(false);">Measurement Location Preferences</a> dialog. The DLF_Name/MLF_Name is an attribute that is stored with the DLF/MLF.
                        </p>
                     </div>
                  </td>
               </tr>
            </table>
         </li>
         <li>
            <p class="para_item">Specify the Section Plane or choose the Inherit Section Plane button. (For Surface DLF only. Skip this step for Hole/Slot/Pin DLF.)</p>
            <p class="para_item">Click the Specify Section Plane button to specify the cross section that the DLF should fall within. The Datum Plane dialog appears. You are cued to select an existing datum plane or create a new datum plane. You can</p>
            <ul>
               <li>
                  <p class="para_item">Select an existing datum plane directly in your graphics window.</p>
                  <p class="para_item">OR</p>
               </li>
               <li>
                  <p class="para_item"> <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/palf.html#location_feature_palf_dlf_cplane');return(false);">Create a new datum plane</a>.
                  </p>
               </li>
            </ul>
            <p class="para_item">The DLF direction vector is snapped to the selected datum plane.</p>
            <p class="para_item">You can also inherit a datum plane from an existing DLF. This lets you use a datum plane previously specified for another DLF. When you choose the Inherit Section Plane button, the single selection dialog appears for you to select a previously created DLF in the part. You are prompted to specify the type of relationship the Surface DLFs must share.</p>
            <div class="figure">
               <p align="center"><img align="bottom" src="graphics/dlf_inh_pl.gif"></p>
            </div>
            <div class="title_figure">Inherit Section Plane Dialog</div>
         </li>
         <li>
            <p class="para_item">Specify Relationship.</p>
            <p class="para_item"><img align="bottom" src="graphics/dlf_rel1.gif" border="0"></p>
            <p class="para_item">Click the Specify Relationship button. The Specify Relationship dialog appears. Assign relationships shared by DLFs:  <img align="bottom" src="graphics/dlf_flush.gif" border="0">,  <img align="bottom" src="graphics/dlf_gap.gif" border="0"> or  <img align="bottom" src="graphics/dlf_ns.gif" border="0"></p>
            <p class="para_item">The relationship is captured as an attribute on both DLFs where the Type and related DLF are indicated. The Specify Relationship dialog is automatically invoked if you have chosen the Inherit Section Plane button during creation. The choice of relationship type No Relation is available for times when you need to share cross sectional planes but not the relationship. This does not create a relationship attribute.</p>
            <p class="para_item">You can also break the relationship by choosing  <img align="bottom" src="graphics/dlf_nr.gif" border="0">.
            </p>
         </li>
         <li>
            <p class="para_item">Set Characteristics.</p>
            <p class="para_item">Click the Characteristics button. The  <a class="links" href="javascript:void(0)" onclick="top.openFile('mpaw/ref_dat_char.html');return(false);">Datum Characteristics</a> dialog appears. Using this dialog you can add attributes to the DLF. Each site controls the list of available attributes by modifying the ugdatum.dpx file found in the ugprocess_aid directory. A set of generic attributes is supplied with the module.
            </p>
         </li>
         <li>
            <p class="para_item">Specify the vector direction. (For Hole/Slot/Pin DLFs only. Skip this step for Surface DLF.)</p>
            <p class="para_item">MPAW calculates the direction based on the input geometry. In cases where it is unable to calculate the direction, you are cued to specify the vector direction. Even if MPAW calculates the direction, you can specify a direction of your choice, in which case the DLF is created in the direction you specify.</p>
            <p class="para_item">Click  <img align="bottom" src="graphics/dlf_dia_svdir.gif" border="0">. The Vector Constructor dialog appears using which you can specify the direction.
            </p>
         </li>
         <li>
            <p class="para_item">Turn the Mature toggle ON to assign an attribute with a value of &quot;True&quot;. This can be used to indicate whether the datum is in a stable location or expected to be moved by further engineering changes. This is strictly a user-controlled attribute and MPAW makes no attempt to verify the validity of this setting.</p>
         </li>
         <li>
            <p class="para_item">Turn the Freeze Location toggle ON to fix the DLF in its current location and disallow repositioning. The addition or subtraction of geometry to the DLF set has no bearing on the DLF once this button is toggled ON.</p>
         </li>
         <li>
            <p class="para_item">Turn the Non-Associative toggle ON to break all associativity between the DLF and its creation geometry.</p>
            <table border="0">
               <tr>
                  <td valign="top" align="left"><img align="left" src="../graphics/warning.gif" alt="Warning" title="Warning"></td>
                  <td valign="bottom" align="left" width="100%">
                     <div class="para_warning">
                        <p class="para_warning_body">Once associativity is broken, there is no way to restore it.</p>
                     </div>
                  </td>
               </tr>
            </table>
            <table border="0">
               <tr>
                  <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
                  <td valign="bottom" align="left" width="100%">
                     <div class="para_note">
                        <p class="para_note_body">MPAW automatically calculates the DLF direction and adds it as an attribute to the DLF/MLF feature set. You can edit the DLF direction in the Edit mode.</p>
                     </div>
                  </td>
               </tr>
            </table>
         </li>
         <li>
            <p class="para_item">Choose  <img align="bottom" src="graphics/ok.gif" border="0"> or  <img align="bottom" src="graphics/apply.gif" border="0">. Choosing Apply keeps the dialog open and retains the DLF type. The Name and Section Name are retained from the previous data. Choosing OK inserts the DLF and closes the dialog.
            </p>
         </li>
      </ol>
      <p class="para_division">Surface DLF: MPAW creates the datum plane, if it is not already present, and inserts the DLF at the center of the intersection curves obtained by intersecting the overlap region of the set of faces and the section plane. If curves are used, the Surface DLF is located at the join curve's mid param of all the input curves. If there are multiple intersection curves, due to holes or slots on the face, MPAW creates the DLF at the mid-point of the first intersection curve and is associated with the face. If any of the objects selected in a set are curve objects, MPAW associates the DLF with the curve or face without calculating the overlap region.</p>
      <p class="para_division">A feature set named DATUM_LOCATION is created in the part file and is visible on the Model Navigator dialog. The DLF is given a unique name and attributes, such as direction, are stored on it.</p>
      <table border="0">
         <tr>
            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
            <td valign="bottom" align="left" width="100%">
               <div class="para_note">
                  <p class="para_note_body">MPAW performs validation checks. If the datum violates any of the rules or standards, the DLF is highlighted and marked as non-standard.</p>
               </div>
            </td>
         </tr>
      </table>
      <table border="0">
         <tr>
            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
            <td valign="bottom" align="left" width="100%">
               <div class="para_note">
                  <p class="para_note_body">If you convert the entire referencing object to faces instead of curves, MPAW performs intersections to calculate the overlap and re-associate the Surface DLF to the intersection curve between the overlap and the section plane. The Surface DLF is attached to the mid-point of the first intersection curve.</p>
               </div>
            </td>
         </tr>
      </table>
      <table border="0">
         <tr>
            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
            <td valign="bottom" align="left" width="100%">
               <div class="para_note">
                  <p class="para_note_body">If you have turned the Non-Associative toggle ON, MPAW removes all associativity to the DLF and any update of the dependent geometry does not update the DLF location. You can use this option to create a much lighter model and to notify that the design of the DLF is frozen. Only limited editing, such as attributes, is allowed on non-associated DLFs.</p>
               </div>
            </td>
         </tr>
      </table>
      <div class="title_division">Editing</div>
      <p class="para_division">To edit a DLF or MLF</p>
      <table border="0">
         <tr>
            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
            <td valign="bottom" align="left" width="100%">
               <div class="para_note">
                  <p class="para_note_body">The information in this section is valid for MLF as well. All the dialogs and system reactions described below are the same for MLF with the exception of the feature name and dialog title.</p>
               </div>
            </td>
         </tr>
      </table>
      <ol type="1" start="1">
         <li>
            <p class="para_item">Access the Datum/Measurement Location dialog in the Edit mode by performing one of the following steps:</p>
            <p class="para_item">On the menu bar, choose Edit-&rarr;Feature-&rarr;Parameters. The Edit Parameters dialog appears. On the Edit Parameters dialog, select the DLF you want to edit.</p>
            <p class="para_item">OR</p>
            <p class="para_item">Click the Model Navigator icon on the standard NX toolbar. On the Model Navigator dialog, select the DLF you want to edit.</p>
            <p class="para_item">The Datum / Measurement Location dialog appears, displaying the values entered/set while inserting the feature.</p>
            <table border="0">
               <tr>
                  <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
                  <td valign="bottom" align="left" width="100%">
                     <div class="para_note">
                        <p class="para_note_body">All the options/fields can be modified. Attributes can be edited on DLFs through the interface.</p>
                     </div>
                  </td>
               </tr>
            </table>
         </li>
         <li>
            <p class="para_item">Modify the DLF as required.</p>
            <p class="para_item">You can:</p>
            <ul>
               <li>
                  <p class="para_item">Add or remove faces from the datum feature. If the DLF's location is frozen, adding or removing faces does not reposition the DLF.</p>
               </li>
               <li>
                  <p class="para_item">Reassociate the DLF to faces in any set by deselecting all the curves in the set and then selecting the face(s). This modifies the location of the feature, depending on the new location of the intersection curve center.</p>
               </li>
               <li>
                  <p class="para_item">Transform the DLF along the overlap surface in the plane of the cross section by manipulating the Percentage along Curve Path scale. If the DLF is associated with curves, you can transform this point along the entire curve path. You can use the Delta Distance value to transform the point along the curve path.</p>
               </li>
               <li>
                  <p class="para_item">Edit the vector direction of the DLF using the Specify Vector Direction button. The Vector Constructor dialog is displayed. Specify the modifications and choose  <img align="bottom" src="graphics/apply.gif" border="0">. The DLF direction is modified.
                  </p>
               </li>
               <li>
                  <p class="para_item">Edit or create a relationship between the current datum and any other datum in the part using the Specify Relationship button.</p>
               </li>
               <li>
                  <p class="para_item">Turn the Freeze Location toggle OFF to &quot;thaw&quot; the DLF's location and allow it to move to reflect changes in the geometry selected for this DLF feature. In case of Surface DLF, the DLF is reattached to the mid-point of the first intersection curve if the first set happens to be a face set, or to the mid-point of the join curve of all the curves input in the first set. In case of Hole/Slot DLF, the DLF is reattached to the centroid of the first set curves or edges input.</p>
               </li>
            </ul>
         </li>
         <li>
            <p class="para_item">Choose  <img align="bottom" src="graphics/ok.gif" border="0"> or  <img align="bottom" src="graphics/apply.gif" border="0"> to save the modifications.
            </p>
         </li>
      </ol>
      <p class="para_division">The DLF is modified. </p>
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