BLOCK & TABLE Group Codes(R12)
2 Block Name
5 Handle
8 Layer Name
10 Insertion (Base) Point
70 Flag Values1=Anon. Block (from hatch, dim etc),
2=Block has attributes present,
4=Block is an external reference,
8=NOT USED,
16=Block is externally dependent,
32=Block is resolved X-ref or dependent of an X-ref,
64=Block definition if referenced.