So, if we have more than 18 keypoint, what should we do? According the grammar of command, there allows 18 keypoint at most.

With the reference of the help document, the reason is identified as the “A” command has a number limited about the keypoint. However, hope rapidly turns into despair after I have tried this command at once. (p.s, the keypoints should be listed in an clockwise or counterclockwise order.)

It’s very useful to mass produce area in APDL when we already know the coordinates of these keypoints. “A” command is used on creating an area through a set of ordered keypoints.