[fasmg] How process undefined symbol?

Hi, i triyng to processate the next line of code:

Code:

Var a,b,c,d:DWORD

But the symbols "a", "b", "c" and "d" are not defined in the code. When i try to compare a symbol:

Code:

if a eq ,
   ...
end if

Fasm G shows me (for example) "symbol 'a' is undefined or out of scope". But my intention is define this symbol after, because i need use it in an expression.

I am new with this macro-proccessor and i dont known exactly how i need use it. This is my code until now...

Code:

macro print text*
        local s
        s = text
        display s,13,10
end macro

macro inc? symbol,step:1
        symbol = symbol + step
end macro

macro parse_var_line return,line&
        local buffer,last,needdatatype,varcount,item
        ;return.COUNT_MEMBER = return.COUNT_MEMBER or 0
        ;return.SCAN_MEMBER = return.COUNT_MEMBER
        last = 0
        needdatatype = 0
        varcount = 0
        define buffer line
        while 1
            ; Splits on tokens and put one in "item".
                match f rest,buffer
                        redefine item f
                        define buffer rest
                else
                        match f,buffer
                                last = 1
                        end match
                end match
                ; To evade code duplication inside of "matchs", i write the "item" verification here.
                ; Item can't be comparated with anything, because is not defined.
                if item eq symbol
                        if needdatatype = 1
                                ;if item eq DWORD
                                ;       return.member#return.COUNT_MEMBER#.type = `DWORD
                                ;end if
                                repeat return.COUNT_MEMBER i:return.SCAN_MEMBER
                                        return.member#i#.type = `item
                                end repeat
                                needdatatype = 0
                        else
                                return.member#return.COUNT_MEMBER#.name = `item
                                inc varcount
                        end if
                else if item eq ,
                        inc return.COUNT_MEMBER
                else if item = @
                        return.member#return.COUNT_MEMBER#.ispointer = 1
                else if item = :
                        needdatatype = 1
                end if
                if last = 1
                        break
                end if
        end while
end macro

define G_VARS
G_VARS.COUNT_MEMBER = 0
G_VARS.SCAN_MEMBER = 0

macro var? line&
        parse_var_line G_VARS,line
end macro

; Code to process.
var a,b,c:DWORD

; Shows in console the number of members or "variables" defined.
print "0"+G_VARS.COUNT_MEMBER

; Shows variable names.
repeat G_VARS.COUNT_MEMBER
        print G_VARS.member#%#.name
end repeat

Edit: I tried to use "defined", but the "item" symbol can be a (for example) comma (,) and this makes an error.

Sorry for my bad english. And thanks for your help.