Unknown SAB tag 21

[rurban]

Missing support for tag 21 (enum <identifier>) in ASM data.

Example: https://forums.autodesk.com/t5/autocad-forum/autocad-modeling-errors/td-p/7240558 "new block.dwg"

...
color-adesk-attrib $-1 $-1 $-1 $-1 $327 $1 #
intcurve-curve $-1 $-1 $-1 F { exact_int_cur ERROR: Unknown SAB tag 21
ERROR: Unknown SAB tag 0
ERROR: Unknown SAB tag 0
ERROR: Unknown SAB tag 0
ERROR: Unknown SAB tag 0
nurbs $2 ERROR: Unknown SAB tag 21
ERROR: Unknown SAB tag 0
ERROR: Unknown SAB tag 0
ERROR: Unknown SAB tag 0
ERROR: Unknown SAB tag 0
$2 0 $2 0.0272823 $2 8.87474 18.7907 1.75 1 8.89245 18.7769 1.73056 1.05245 8.90777 18.765 1.71474 1.09939 0 null_surface null_surface nullbs nullbs F F $0 $0 $0 $0 I 1 I 0 } F F #

Just guessing what the exact format is:
The enum seems to be the previous identifier.
e.g. exact_int_cur <21> $0 means the identifier int_cur
has the enum value exact and a long constant $0. but nurbs $2 <21> $0?

This example throws now "Bad entity layer"