Juniper Networks Protocols frequently have fields where the contents are a series of bits that have specific meaning. When modeling operational state for such protocols in YANG, the 'bits' YANG built-in type is a natural method for modeling such fields. The YANG 'bits' built-in type is best suited when the meaning of a bit assignment is clear. When bits that are currently RESERVED or otherwise unassigned by the protocol are received, being able to model them is necessary in YANG operational models. This cannot be done using the YANG 'bits' built- in type without assigning them a name. However, YANG versioning rules do not permit renaming of named bits. This draft proposes a methodology to represent unknown bits in YANG operational models and creates a YANG typedef to assist in uniformly naming such unknown bits.