I have the situation that data of multiple devices is served by one SNMP gateway. So if have to use dynamic indexes to find the OID to be used. This looks for example like this:

.5.1.2.1 = STRING: "DEV1_VAL_A"
.5.1.2.2 = STRING: "DEV2_VAL_A"
.5.1.2.3 = STRING: "DEV3_VAL_A"

.5.1.3.1 = INTEGER: 1
.5.1.3.2 = INTEGER: 2
.5.1.3.3 = INTEGER: 3

So I tried using dynamic indexes with the hostname macro as follows:

SNMP OID: .5.1.3["index", ".5.1.2", "{HOST.NAME}_VAL_A"]

Zabbix doesn't substitute this macro. So the item gets unsupported.

In the macro support overview it's not clear if this macro is supported there. But I think it should, especially as it works when using a user defined macro like follows:

SNMP OID: .5.1.3["index", ".5.1.2", "{$HOST_NAME_PREFIX}_VAL_A"