This read-write value, ranging 1 to 160, specifies the number of significant bits in the associated svcNodePrefixPrefix, defaulting to 8 times the prefix octet string's length if not otherwise set, since a prefix match may need to be shorter than the full octet-aligned string (a partial-byte prefix match). This lets the switch distinguish a longer, more specific prefix match from a shorter, broader one for routing purposes, similar to a subnet mask concept applied to address prefixes. An engineer configuring a broad catch-all node prefix covering a whole area code would set svcNodePrefixNumBits lower than the full byte-aligned default to make the match intentionally less specific.