Is this even possible.
Example:

column A column B

B200 custname
B201 custname
C202 custname
C203
A204 custname
A205 custname

I can add up All items for hire by their code number,
I can add up All customers by counta Column b
I can add up all available code# available by countblank (Column b)
( If blank in column B - that item is available)

But how could I count all available C items ( we have A.B.C and D)
as in the above example it's return 1 available item in the "C" range.
Is it possible to Count an item only if there's a "blank" alongside in column B?
that way I could I could add up the # of C available ( or A or b or D )
Hope I'v expained that clearly ~
Many thanks.