The stdvia property (number 7160) is applied to standard via instances and sub-masters. The OpenAccess translator will transparently convert these to the corresponding OpenAccess forms when writing to OpenAccess, and vice-versa. A string with very similar format to the property string is used by the OpenViaSubMaster script function. The property string syntax is described here.
There are actually two formats, that will be referred to as the old and new formats. The old format uses OpenAccess keywords and is friendly for humans, the new format uses a code and is more compact. Xic will always write the new format, but will read either format.
The property string consists of one or more space-separated text tokens. In either case, the first token is the name of the standard via, as given in the definition in the technology file. The remaining terms represent the numerical parameters that are different from the defaults given in the standard via definition. There need not be any additional tokens, in which case the via has all default values. More commonly, tokens follow the via name that provide alternate values.
In the old format, a token takes one of the forms
keyword:valueThe value indicates an integer representing a dimension in internal units.
The new format assigns each numeric value a lower-case letter. A token consists of the letter, followed immediately by the numeric value in nanometers. The number is printed in a format which removes trailing zeros and decimal points.
|new format key letter(s)||old format keyword|
The new and old formats can not be mixed, all tokens must follow one format or the other. The cases with two letters correspond to the keywords with two values, and the values represent dimensions in the X and Y directions.
M2_M1 CutRows:2 CutColumns:2 Layer1Enc:40,60
M2_M1 c2 d2 h60
The two strings are equivalent if 1) the database resolution is 1000 so that the internal unit is nanomenters, and 2) the default layer 1 enclosure in the X direction is 40nm.
When a sub-master is created, it is given a cell name that is the same as a new format property string with the space stripped out, and the characters `- ' (minus) and `.' (period) replaced by `m' and `p', respectively.
The OpenViaSubMaster script function takes a string in almost the same format, the only difference is that the via name token is not present. Effectively, the via name is passed as the first argument, and the rest of the string (if anything) is passed as the second argument. Either new or old format is acceptable.