For the post-WW2 era, what determined the sizes of the round or button head compression rivets used in building freight cars?

What were the typical shank and head diameters used? . . . example: 1920s to 1940s gondola cars?

I presume the spacing or pitch was based on where the stresses (or observed failures) were typically the highest?

Do the raised rivet head decals reference the shank or their visible head diameters.

Were there standard practices published by the Master Car Builder's or ARA for rivet sellection, spacing, hole sizes, etc.?

Al Kresse