I have created a macro with a loop which periodically has to check a
spreadsheet cell (Boolean value) in order to branch to different
sub-routines. Since VBA makes a distinction between 'parameter' (structure)
and 'argument' (value), the parameter definition in the sub-declaration line
does not allow for its value to be tested, eliciting the error: "argument is
not optional". How then does one test for a cell's value while in a macro?
The cell in question toggles between 0 and 1 depending on data coming in via
DDE. It determines what action should take place in the macro.

I know that the value of an argument can be passed manually to a macro, as in,

-Call (macro-name) (argument),

however, this is not practical in this case because of the large amount of
data involved. What then is VBA's equivalent for the 'procedural' line:

-If (cell/name) = True Then...../Else...../Endif?

Any suggestions will be appreciated.