CAD tip # 3638:

For multi-line texts you can use the control characters \P (new line) a \X (above/under dimension line). These characters can be combined and mixed with the control code for the dimensioned value: <>. The dimensioned value and \X can be used only once in the dimension text.

A complex example is the following dimension text (enter it e.g. into the Text override field in the Properties window for the selected dimension entity):

  
first line\Psecond line (P) with dim value: <>\Pthird line (P)\Xfourth line (X)\Pfifth line (P), <> now ignored, \X second X is ignored