asn.1

Interpretation of Size Constraints " , ...))" for SEQUENCE OF types in ASN.1

I am working with ASN.1, I found a variable with definition:

A ::= SEQUENCE (SIZE(1..3, ...)) OF FOO

Do it means that A is a list from 1 to infinite of FOO variables?

Solution

  • The ellipsis means that type A is extensible (you may have more than 3 in the future).

    I think this is only meaningful if you are using PER (Packed Encoding Rules) where some constraints influence the way data are encoded/decoded.

    As SIZE in SEQUENCE OF is what is called a PER-visible constraint, the encoding technique will be different if you send an array with more than 3 elements.