Hi, I'm having dificulties fitting the formula in data validation.

The condition should be :

1. A-TFG-1234(a or ab)
2. B-TFG-1234(a or ab)
or
3. ABC1234 - (TFG1234 is not allowed)

Note:

For No.1 and No. 2 :
"A-TFG-" or " "B-TFG-" is mandatory.
1234 is numeric only
(a or ab) any alphabets (lowercase or uppercase are allowed)
minimum 10 character, maximum 12 character
sample : A-TFG-4675, B-TFG-6544KL or B-TFG2344G

For No. 3
ABC is (a|A..z|Z only) but TFG is not allowed
1234 is a number
max 7 character
sample : BTU3456, wrt2231
sample : TFG2245 (is not allowed)

Below is my code:

=OR(AND(OR(LEFT(C10,6)="A-TFG-",LEFT(C10,6)="B-TFG-"),ISNUMBER(MID(C10,7,4)*1),AND(LEN(C10)=10,NOT(I SNUMBER(MID(C10,11,1)*1)))),(AND(ISNUMBER(RIGHT(C1 0,4)*1),NOT(ISNUMBER(LEFT(C10,1)*1)),NOT(ISNUMBER( MID(C10,3,1)*1)),LEN(C10)=7,LEFT(C10,3)<"TFG")))

still not cover everything due to the lack of space.

Anybody can simplify this code?
Please help.

Thank you