This is based on a discussion with @nrnhines in #1957. By looking at the usage and implementation of the INDEPENDENT block, we concluded the following:

• In INDEPENDENT block, usage of variable t only makes sense
• Most of the MOD files use the variable t. There are few that use v but that's not required.
• Looking at the implementation, declaring a variable as an independent only mark (treat) that variable as ASSIGNED.
  • but variables like t and v is used and they are already available as RAMGE/ASSIGNED, use of the INDEPENDENT block is doing nothing today.
• Not the rest of the production FROM x TO y WITH z (unit) has no effect.

So we decided to do the following:

• We will keep the production in the bison parser
• We should just check if the independent variable is t. If this is not the case, we should throw a warning like: Warning: Only variable t should be used in the INDEPENDENT block but XX is used
• Apart from the above check and issuing the warning, we should remove all other code related to the INDEPENDENT construct.