REDRAW is a command similar to REGENerate. It runs faster than REGENerate because the computer only thinks about the part of the drawing that is showing on the screen and uses the short-cut of drawing faceted lines instead of smooth curves. This way it redoes the drawing on the screen more quickly than REGENerate. It is useful when you want to quickly remove left over vertex marks from the screen or to reveal a line that was on a lower layer of the drawing that appears to have "disappeared" because you MOVEd the line on top of it.
You will probably not notice a major difference between the two commands unless you have a very large drawing. Back in the olden days when we were running on 286 and 386 Mghz computers, this was an important difference.
CPM has a very useful function known as BLOCKs. All the Instruction and Marking Symbols included with CPM are INSERTed as BLOCKS into your pattern drawing. If you wish to bring a pattern created in a different drawing file, into your current drawing file (for layout, perhaps), you will INSERT it as a BLOCK into your drawing. You can create any drawing object you wish to use as a BLOCK, save it as a drawing file and reuse it any time you want.
Anytime you INSERT a BLOCK into a drawing file, that BLOCK is added to the drawing file database. Even if you ERASE the image of the BLOCK from the drawing file later on, the drawing file database keeps the BLOCK image in its database unless you use the PURGE command (found on the FILE pop-down menu) to remove it from the database.
To create a drawing object to be used as a block in a specific drawing file, you need to begin by created the drawing object on the drawing page of the file you plan to use the block in.