Issuing locks the revision inside the document: the title block writes itself, the regions protect themselves, and the issued copy stays readable after work restarts on the next one.
SheafMER-CALC-014·Meridian Engineering3 LOCKEDRT
An issued revision is read-only. Opening one shows the document exactly as it was issued.
Pad footing — bearing pressureMeridian Engineering · job 2418 · EN 1997-1