What is the closer latching feature?

Snap Action Closing - Installed as directed, the door is in the maximum latching position. For a smoother and quieter latching, hold door open about 8" and slide hold-open washer to tube. 

IF/

Two hole Jamb bracket:

Remove the short connecting pin from the jamb bracket and relocate closer rod in rear hold as shown in Figure B. Push door open further and slide hold-open washer back toward jamb bracket. Closer is now ready for normal use.

OR/

Two hole end plug:

Remove the long connecting pin and relocate door bracket to rear hole of door closer as shown in Figure C. Push door open further and slide hold-open washer back toward jamb bracket. Closer is now ready for normal use.