As of ASN1C version 5.7, ASN1C90 is now an option built-in to the standard ASN1C executable program. This option is -1990. Therefore, specifying ‘asn1c <file> -1990’ on the command-line is equivalent to using the old ‘asn1c90’ executable program. The remaining text in this section refers to using ASN1C with the -1990 option.

ASN1C when used with the -1990 option contains extensions to handle the older 1990 version of ASN.1. Although this version is no longer supported by the ITU-T, it is still in use today.

This version of the compiler also contains logic to parse some common MACRO definitions that are still in widespread use despite the fact that MACRO syntax was retired with this version of the standard. The types of MACRO definitions that are supported are ROSE OPERATION and ERROR and SNMP OBJECT-TYPE.