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String Masking

Selection mask tables enable you to select strings in groups from a model for subsequent processing. The mask may be alphabetic, numeric or contain blank characters or any of the special characters valid within a string name. For an inclusive mask the string is accepted for further processing; for an exclusive mask the string is rejected. A selection mask table is used to store more than one mask. When masking is involved, the masks are processed in the order in which they appear in the table. With disciplined choice of string names, masks can be very useful.

Adding an Entry to a Mask Table

  1. From Tools on the MX menu bar, select "Selection Mask Tables...".
  2. Use New, or Open to load an existing mask table.
  3. Enter the string name. If you type a partial string name , you can either use "?" or spaces for the wildcard characters.
  4. Select the Type of Mask from the list.
  5. Click the Add to Table button.
  6. Use Save or Save As to save the defined mask table.
  7. Click Done to close the panel.

Creating and Editing a Mask Table

The order of the masks in the table is important. MX checks names against each mask in the table in the order in which the masks are found in the table. As soon as a mask is satisfied, no further tests are made for any particular string. It is possible for a string to satisfy more than one mask, the more restrictive mask should appear first. Usually this will be the mask with the most non-blank characters. A string will be included if, on reaching the bottom of the selected mask table, no mask has been satisfied.

A maximum of 1,000 masks may be created in the selection mask table.

When you have finished creating the table, you should save your changes.

Refer to MX Help for more details about string masking.

Selection Mask Table Examples

Example 1

  • Include H???
  • Include F???
  • Exclude ????

This will select H and F strings from the model. All other strings will be ignored.

Example 2

  • Include PTR?
  • Exclude P???
  • Include ????

Of all the P strings in the model, this will select only the strings with the characters PTR and any fourth character. All strings other than P will also be included.

Example 3

  • Exclude ?T??
  • Include P???
  • Include ST??

This example contains an error because the first mask excludes all strings which have the second character as T, whereas the third mask includes strings beginning with ST. MX will recognize this and indicate an error. To correct the table, the last mask should be moved to the top of the table.

New Hampshire Department of Transportation
PO Box 483  |  7 Hazen Drive  |  
Concord, NH  |  03302-0483
Tel: 603.271.3734  |  Fax: 603.271.3914