This is GDS2, a module for creating programs to read, write, and manipulate GDS2 (GDSII) stream files. GDS2 should be able to handle any size gdsii file but I would consider it too slow for anything larger than a few megabytes in size. If your files are are closer to the gigabyte range please check out my gdt programs at: http://sourceforge.net/projects/gds2/ which you can use to open and process GDS2 files as a pipe from Perl.