CAD tip # 10015:

Filtered selection of objects from the whole DWG drawing database can be performed with the LISP function (ssget "X") - specifically e.g. all circles anywhere in the drawing can be selected using:

(ssget "_X" '((0 . "CIRCLE")))

or all objects with the assigned color "red" using:

(ssget "_X" '((62 . 1)))

or all objects in the layer "ABC" using:

(ssget "_X" '((8 . "ABC")))

You can also use combinations of the AND, OR, XOR and NOT conditions plus individual object properties (lookup their codes in the DXF specification). E.g. (0 . "LINE,SPLINE,LWPOLYLINE") or simply (0 . "*LINE") selects all types of line entities, the condition (0 . "CIRCLE")(62 . 1) selects only red circles, or (-4 . "< NOT") (0 . "TEXT") (-4 . "NOT>") selects all but single-line texts.

This construction can be then used in combination with the function for grip-selection of objects - (sssetfirst) - and with the Properties palette (Ctrl+1), where you can modify the requested property in all selected objects. So e.g. recoloring of all otherwise not recolored dimensions in the model and in all layouts can be done from the Properties palette after you select all such dimensions using the command:

(sssetfirst nil (ssget "_X" '((0 . "Dimension")(62 . 256))))

Now, using the Properties palette, you can modify any property common to all selected drawing entities, e.g. color, layer, scale, etc.