Drop_Handle$

str-var = Drop_Handle$(Line-ref \| "ALL")
Operands:	line-ref	A reference to a data line to which a Line Handle is to be removed. The LineRef can be a numeric Line Pointer, or it can be a string containing a normal label (".ABC"), a pseudo-label (".123"), the string form of a Line Pointer ("!123"), or a Line Handle name ("._123"). A Tag name(":ABC") cannot be used. If "ALL" is passed as the label-ref, it is a request to release all existing Line Handles.
Returns:		If the LineRef is a valid reference to a data line, and the data line currently has a Line Handle assigned to it, the string form of its current Line Handle ("._123") is returned, and RC = 0. If the LineRef is valid but the line had no Line Handle, a null string is return, and RC = 0, If the LineRef is an undefined label or refers to a non-existent data line or to a line that is not a data line, a null string is returned and RC has a non-zero value. A call of Drop_Handle$("ALL") returns a null string and RC = 0.
Special Notes		Once a Line Handle is dropped, its value is not used again, unless Drop_Handle$("ALL") is issued, at which point new Line Handles are assigned starting with handle ._1. The Drop_Handle$ function supersedes Release_Label$. All new macros should call Drop_Handle$.