Insert block:
_cmddia 0 ........... (turns off dialog boxes)
_INSERT ............. (places a named block into the current drawing)
demo_block ........ (the named block)
0,0 ...................... (block insertion point)
1 ......................... (X scale factor)
1 ......................... (Y scale factor)
0 ......................... (rotation angle)
_cmddia 1 .......... (turn on dialog boxes)