Bolt length for pretension in AISC 348 1

[canwesteng]

AISC 348/RCSC spec gives the amount of rotation for turn of the nut based on the bolt length. Is this the length of the bolt itself or the length of connected parts between the bolt head and nut? It doesn't make sense to me that the length of bolt past the nut affects the amount of pretension afforded by turn of the nut, since it is unstressed.

 

[jhnblgr]

Flat faces under bolt head and nut.

https://cdn.docsie.io/document/workspace_xDo6jFMbRlfjgA3QD/doc_SOJ6SQXTep0RsYduq/file_XTQitHzjysNafitTr/tds_012_turn_of_nut_installation_6cb35249-37e6-76b7-213a-65d9523f0e6d.pdf