If you have a chance to carefully read SNMPv2-TC,
http://www.ietf.org/rfc/rfc2579.txt
you will see that there are already common enum types defined, such as TruthValue.
TruthValue ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION
"Represents a boolean value."
SYNTAX INTEGER { true(1), false(2) }
By importing such enum definitions in your MIB document or define your own, you can use/reuse them throughout the file.