This standard BS ISO 11639:2010 Aerospace. Part numbering for hose assemblies is classified in these ICS categories:
49.080 Aerospace fluid systems and components
This International Standard specifies a hose-assembly designation system and presents a part numbering scheme for aerospace fluid-system hose assemblies.
Standardization on certain numbering systems provides for numbering simplicity, ease of interchangeability, and the suppression (as required), standardization and limitation of usable codes.