Material on Habitability Improvement Program Drawings are identified by Find Numbers. 
The Commodity Handbook posted here lists all of the Find Numbers in a searchable form. 
The complete unique Find Number (FN) consists of the Find Number and Discipline, such as FN 518 ARR. 
The four primary disciplines are Arrangement (ARR), Electrical (ELEC), Pipe (PIPE) and Ventilation (VENT). 

This system has been refined over more than 25 years as a Common Parts Catalog.  Standardizing descriptions across different drawings has made it possible to establish long term procurement contracts, to facilitate production line manufacturing with consistent high quality, (instead of inconsistent small batch procurement), and improve efficiency throughout the design and supply cycle. 
Find Numbers are defined to suit modular procurement and installation, and take into account features to suit efficient installation.

More detail: 
Many of the major vendors for Shipboard Habitability materials are familiar with Find Numbers, and recognize a Find Number as a complete description.  Other activities are encouraged to use and interface with the Find Number system as a Common Parts Catalog in order to encourage standardization and efficient ordering and administration of materials. 

Descriptions are continually updated to reflect changing specifications and industry trends, with care to ensure compatibility between existing material, current and future drawings.  If a Find Number needed to change so much that it would no-longer be interchangeable, then a new Find Number would be assigned.  What is posted here is used as a Contract Line Item description.  Standardized amplifying Notes are used as an additional part of the specification in requisitions and contracts.  For technical material questions call or E-Mail Habitability Support at (757) 460-4449.