I have to contruct a search but have only got half way

I need to search on a form and get results for
(fieldA = a, fieldA = b, fieldA = c, fieldA = d) OR (fieldB = e or fieldB = f)

which is the easy bit
I now have to run an extended search with a NOT for the same fieldA and FieldB

(fieldA = g, fieldA = h, fieldA = i, fieldA = j) OR (fieldB = k or fieldB = l)

Is it an OR NOT or and AND NOT

(fieldA = a, fieldA = b, fieldA = c, fieldA = d) OR (fieldB = e or fieldB = f) but not these
(fieldA = g, fieldA = h, fieldA = i, fieldA = j) OR (fieldB = k or fieldB = l)

the first part it is actually coded as
(fieldA = a or fieldA = b or fieldA = c or fieldA = d) OR (fieldB = e or fieldB = f)

dont know if I need to do anything clever with the brackets either

((fieldA = a or fieldA = b or fieldA = c or fieldA = d) OR (fieldB = e or fieldB = f))

well we got the above sorted and then a request was issued for a select with NULLs OR NULLS which we then pointed out was rather silly as the data extract went from a few to a few thousand so they gave up and the request was withdrawn .......