13.3. Rules for Textual Conventions

Sub-typing of Textual Conventions (see [3]) is allowed but must be valid. In particular, each range specified for the textual convention must be a subset of a range specified for the base type. For example,

     Tc1 ::= INTEGER (1..10 | 11..20)
     Tc2 ::= Tc1 (2..10 | 12..15)       -- is valid
     Tc3 ::= Tc1 (4..8)                 -- is valid
     Tc4 ::= Tc1 (8..12)                -- is invalid