In a P&ID drawing, pipe lines are grouped based on the tag value of the Pipe Line Group.
The default tag value of the group is the Line Number. Also, the default tag value of a line segment includes the line number
(for example: in [Size-Spec-Service-Line Number]).
This means that by default, setting the line segment tag also assigns the line group. The other way around, it means that
assigning the line group partially sets the line segment tag.
The above image shows line number 101 and an unassigned ( ? ) line selected.
You can use slregoup to set the unassigned line to an existing line number (line group tag value).
The selected unassigned line number is now in line group 101, which partially sets the default line segment tag.
NoteWith the introduction of slregroup in AutoCAD Plant 3D Extension 2, pipe lines are no longer automatically added to existing groups if you assign identical
tags. Instead, a Tag Already Assigned dialog box displays and the tag assignment is cancelled.
Line Group Tag Management
No two different schematic line groups can have the same tag because the tag identifies the group. This can prevent you from
assigning an existing line number to a line segment.
If an operation attempts to assign an existing tag and cannot be interrupted, a question mark ( ? ) is added to the tag temporarily.
You can later use the assigntag command or Data Manager to resolve this.
You can use the slgroupedit command to add lines to an existing line. If the default tag format is used, any lines added to the group are assigned the
same Line Number.
You can use Project Setup to modify the tag format of the pipe line group or the line segment.