Workable Gage W14

[slickdeals]

Folks,
What do the 3 numbers 3 - 7 1/2 - 3 represent in the workable gage table for W14x145 to W14-808?

Why is it 3 values instead of one?

 

[civilperson]

This represent the hole spacing for bolts through the flange with the center of the web at the center of the 7 1/2". (Four bolts with three interior dimensions)