Power,
m. is a built-in alias meaning it is a memvar. m. is appended to all memvars implicitly and if you explicitly put it it means you're pointing to memvar variable. This small code might make it more clear :

create cursor test (myvar1 i,myvar2 i)
for ix=1 to 5
  insert into test values (ix,ix*2)
endfor
go top
browse

m.myvar1 = 100
myvar2 = 200
scan
 ? m.myvar1, m.myvar2, myvar1, myvar2, test.myvar1, test.myvar2
endscan

As you can see in assignment it's memvar whether you have 'm.' or not (for table fields you need replace). However if you are querying the value if you don't include 'm.' and there is field var with same name it takes precedence.
Cetin

>Thanks all of you for your help first.
>Nadya, I tried your suggestion:
>copy file temp.txt to (m.lcFileName)
>it works well. Then I tried to skip the "m.":
>copy file temp.txt to (lcFileName)
>it works too. Can you explain to me what does the "m." means? I tried to search it in HELP but failed to find it.
>
>
>>>You could try copy file temp.txt to &filename
>>
>>You don't need to use macro.
>>
>>lcFileName='myfile.txt'
>>copy file temp.txt to (m.lcFileName)