Vol. XIII, No. 2

Fall, 2000

I have recently learned of some new capabilities in AutoCAD that help with layer management. These new search aids are available in Release 14 as well as the current AutoCAD 2000; so I should have known about them before, but here they are:

# for any single number (0-9)
@ for any single alphabetic character (A-Z, a-z)
. for any single non-alphanumeric character (; , ! @ # $ % and so on)
(space) for a space
~ negate what follows
[ ] any single character among those placed inside the brackets
[ - ] any single character in the range specified by a character on either side of the dash
' to treat the following character literally

Of course, there have long been the two common choices:

? for any single character
* for any number of characters

Using all these choices makes it possible to manage layers much more easily. Some examples are necessary; so I will use the layers in the older propylon model, with its lengthy layer names tied to the CSA Layer Naming Convention, to illustrate how these new commands can be used.

The layer names for the model are quite long - 18 characters - and each character in the name has its meaning from position as well as the character in that position. For instance, the second character in a name concerns the "in-situ-ness" of the material included on that layer. The letter I in that position indicates that the material is in situ, and a T is used for trimmed bedrock. An M indicates that the material is in situ but has been moved slightly by natural agents, whereas a P indicates that the material is in a secondary use context and has been moved slightly by natural agents. If the second character is an H, the material is hypothetical but accepted generally, and if a number is used in that position, the material has been reconstructed (with the number indicating a specific scholar).

Previously, I have called up all the in situ material by asking for all material with an I, an M, a P, or a T in the second position. I also ask for the layers with an H in that position if I want to include the virtually certain portions of the model - that means four specifications of layer names: layers with the I, the M, the P, and the T in the second position. With these new aids, I can issue a single specification to call up the layers with any from the list of I, M, P, and T in the second position (or, if I want the hypothetical layer, call up all layers that have a character, not a number, in the second position). Thus, the command would be

or

The old command sequence would have been

When actually working with the model, as opposed to showing it to others, the most desirable feature is likely to be the tilde (~) for indicating a negative. I have often commented that it was very important for me to be able to examine the older propylon model and suppress the layers that did not include marble blocks; that made it possible for me to see what later seemed obvious - that the marble blocks were part of a single project, the poros being a later intrusion. It would have been easier if I could quickly have turned off all that was not marble, not just the poros. The use of the ~ character makes that easy; I could now request that all the non-marble layers be suppressed with a single command:

I might offer more examples here, but I think those familiar with AutoCAD will already have understood the value of these additions to the layer-selection processes.

-- Harrison Eiteljorg, II

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For other Newsletter articles concerning applications of CAD modeling, in archaeology and architectural history, the "CSA CAD Layer Naming Convention," or the use of electronic media in the humanities, consult the Subject index.

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Table of Contents for the Fall, 2000 issue of the CSA Newsletter (Vol. XIII, no. 2)

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