A LAYER record can appear after a STRUCT, and must appear before any of BOX, POLY, WIRE, TEXT in the STRUCT. The layer context will persist until the next LAYER or STRUCT record.
The header flags byte is not used.
The LAYER record contains the following fields:
|?||[lname]||optional layer name|
The layer number and data type are sufficient, and have the same interpretation as in GDSII. Alternatively or in addition, a string giving a layer name can be supplied.