the 70 group is bit encoded group. Below is a list of the bits from the
help files:
Standard flags (bit-coded values):
1 = Layer is frozen; otherwise layer is thawed
2 = Layer is frozen by default in new viewports
4 = Layer is locked
16 = If set, table entry is externally dependent on an xref
32 = If this bit and bit 16 are both set, the externally dependent xref has
been successfully resolved
64 = If set, the table entry was referenced by at least one entity in the
drawing the last time the drawing was edited. (This flag is for the benefit
of AutoCAD commands. It can be ignored by most programs that read DXF files
and need not be set by programs that write DXF files)
--
Bobby C. Jones
http://www.acadx.com