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Are the any special character that isn't supported by either GDS or OAS?

werkwerk
in File Formats

And where can I find such document? Thanks!

Comments

  • werkwerk

    I mean the cell name part, any special character isn't supported? Thanks!

  • RawrRangerRawrRanger

    Hi werk,

    Here's some gds cell naming recommendations
    https://pubs.opengroup.org/onlinepubs/9629499/apdxa.htm
    https://www.artwork.com/gdsii/qis/faq/qis_limits.htm

    As a matter of curiosity, I've also tried to name cells with Emoji in KLayout, the application can handle the characters well (which is expected, since Qt can handle anything), but once you save the files, those invalid chars will be converted to $$$$$ and causes mess.

  • StefanThiedeStefanThiede

    The oasis spec (you might find the draft in web-archives) requires n-strings for cell names.
    n-strings must only contain printable ascii (21-7E), which excludes space, tabs and all other control characters and have a length > 0.
    Since some databases use cell names as filenames, it's good advice to stick to this.

    a-strings are 21-7E with SP(ace) and are used for oasis TEXT.
    This causes issues when converting gds to oasis, because some GDS cell libraries contain TEXT with tabs, newlines or even non printing hex codes.

  • MatthiasMatthias

    For OASIS the allowed characters are well defined, but for GDS there only exist conventions.

    In my experience safe cell names in GDS should be short (<40 characters) and use characters from ASCII letters (lower and upper case, case sensitive), digits and the underscore. "$" is safe to use too. Everything else may or may not cause issues when you send GDS to some foundry or mask maker.

    Matthias

  • werkwerk

    Thanks all for the comment (RawrRanger, StefanThiede and Matthias).

    Hi Mattias,

    We have an extreme test case with special characters in cellname, such as ";". We created the .txt file and loaded it with klayout. All the characters after ";" are strip off. Is this a known issue for ilayout? Thanks for the comment!

    p.s., here's the .txt file:

    HEADER 600 
BGNLIB 7/22/2023 0:20:21 7/22/2023 0:20:21 
LIBNAME LIB
UNITS 0.001 1e-09 

BGNSTR 7/22/2023 0:20:21 7/22/2023 0:20:21 
STRNAME 100x100

BOUNDARY 
LAYER 0 
DATATYPE 0 
XY 0: 0
0: 100
100: 100
100: 0
0: 0
ENDEL 

BOUNDARY 
LAYER 0 
DATATYPE 0 
XY 900: 900
900: 1000
1000: 1000
1000: 900
900: 900
ENDEL 
ENDSTR 

BGNSTR 7/22/2023 0:20:21 7/22/2023 0:20:21 
STRNAME !#$%&()*+,-./0123456789:;<=>?@

AREF 
SNAME 100x100
COLROW 1000 1000 
XY 0: 0
1000000: 0
0: 1000000
ENDEL 
ENDSTR 
ENDLIB
  • MatthiasMatthias
    edited July 2023

    No, that is not a know issue.

    ";" is apparently intended as a comment character. It is allowed inside text strings and property names, but not inside cell names.

    I need to say however, that the text format read is contributed code and I can't say what specification it complies with.

    If you think that is a bug, please raise a ticket on GitHub (https://github.com/KLayout/klayout/issues).

    Matthias

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