Fastener layout terminology in riveted/bolted joints: the imaginary line along which a row of rivets or bolts is placed is called the ______.

Introduction / Context:
Accurate terminology is essential when laying out riveted or bolted connections on shop drawings. The reference line used to position holes influences edge distances, gage (gage) distances, and stagger.

Given Data / Assumptions:

• We refer to the standard naming of the reference line that defines a row of fasteners.
• Common terms exist, but only one is the accepted technical term in this context.

Concept / Approach:
The gauge line (often spelled gage line in some codes) is the reference line parallel to the member edge along which fastener centers are set. Pitch is then measured along this line. Other listed terms are not standard or are used in different trades.

Step-by-Step Solution:

Verification / Alternative check:
Connection detailing manuals show gauge distance (from edge to gauge line) and pitch spacing along the gauge line.

Why Other Options Are Wrong:
“Rivet line” is informal; “scrieve line” and “back line” are not standard for steel connection layout; “pitch datum” is not a conventional term in this context.

Common Pitfalls:
Confusing gauge line with centerline of the member; misapplying edge distance versus gauge distance.

Final Answer:
gauge line