Count unique instances in one column meeting multiple criteria (with OR condition)

I've read most posts on this forum for this topic, but still can't seem to get my formulas to work. The answer may be a pivot table, but I'd like to at least know I've tried all my options.

OK - the spreadsheet actually has 17 columns, but I can't do any of the other calculations without being able to get this one right, so I'm only including these two for now.

Column A - Position
Column B - Grade

- Count unique instances in Column A that are either "O*" or "W*" in Column B

- Count unique instances in Column A that are "E*" in Column B

I don't think wildcards can be used though. I can get it count unique instances (=SUM(IF(FREQUENCY(A2:A48,A2:A48)>0,1)) - but it doesn't seem to work when I try to add multiple criteria.

I've attached the most basic example of what I'm looking for. Any help will be greatly appreciated!

As it my wont I went for an overly complicated array formula:

=SUM(INDEX(IF(ISNUMBER(FIND(LEFT(B2:B48,1),"OW")),1,0),0)*(IF(ROW(A2:A48)-1=IFERROR(MATCH(A2:A48,INDEX(IF(ISNUMBER(FIND(LEFT(B2:B48,1),"OW")),A2:A48),0),0),0),1,0)))

Confirmed with Ctrl-Shift-Enter, naturally.

Thank you! This did work - now trying to combine it with other formulas. Will post when I have the other fields filled out (my spreadsheet is held on another network).

Thanks again!

OK - I've attached an "updated" spreadsheet. Any help will greatly save the tax payers some $$$.

The box to the right on the spreadsheet is what I'm filling out.

I used the formulas you gave me Fotis (thank you!!), but of course and am having trouble combining them with what I need for the next field - "Filled".

Out of the "Authorized" number - how many cells in Column G have text? I will use this for Vacant as well (except it will count the empty cells). does this make sense?UNIQUES.xls

My apologies for the long break - had to travel unexpectedly.

The expected result for Filled is:

Mil Off: 14
Mil Enl: 13

Filled: Count the unique number in Column B (Position #) that also has a name in Column G (Incumbent Name). The Mil Off (“O” or “W”) and Mil Enl (“E”) still have to counted separately.
Note: Would it simplify things to have a “status” column (Filled, Vacant, Double)? And then use that column to complete the other formulas?

Vacant: Count the unique number in Column B (Position #) that also has a "Blank" in Column G (Incumbent Name). The Mil Off (“O” or “W”) and Mil Enl (“E”) still have to counted separately.

Double: Count the number of Positions in Column B that occur more than one time. Each instance of the number should be counted. The Mil Off (“O” or “W”) and Mil Enl (“E”) still have to counted separately.