Any joint created internally by the program (say, due to auto-meshing) has a "~" prefix. The table "ANALYSIS RESULTS > Element Output > Objects and Elements > Table: Objects and Elements - Joints" reports the coordinates for the point elements along with the name of the point object from which the joint element was created. If the joint element was not created from a point object, but instead was created as a result of internal meshing by the program, then JointObject entry is blank for this element in the table. The table can be displayed via "Display > Show Tables" menu command.
You can also display the internal joints graphically via "Define > Set Display Options" menu command which will open "Display Options For Active Window Form". Then check "Labels" and uncheck "Invisible" under Joints heading, and check "Show Analysis Model (If Available)" under Miscellaneous heading.
