Control
CIF subroutines can be overwritten by deleting them and then redefining them. The DD
statement (delete definition) takes a single parameter and deletes every subroutine that has a number greater than or equal to this value. The statement is useful when merging multiple CIF files because designs can be defined, invoked, and deleted without causing naming conflicts. However, it is not recommended for general use by CAD systems.
Extensions to CIF can be done with the numeric statements 0
through 9
. Although not officially part of CIF, certain conventions have evolved for the use of these extensions (see Fig. B.5).
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FIGURE B.5 Typical user extensions to CIF. |
The final statement in a CIF file is the END
statement (or the letter E
). It takes no parameters and typically does not include a semicolon.
Read more about this topic: Caltech Intermediate Form
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