What is the general division of work that distinguishes the work of the structural steel…

What is the general division of work that distinguishes the work of the structural steel subcontractor from the miscellaneous metals subcontractor? If a steel member is directly attached to the primary steel structure and the

fabrication can be completed in the shop so the member can be simply and quickly bolted and/or welded in the field, which subcontractor should be responsible for the work?