create subtype automatically

[Stevie]

As a total beginner in Access, I have managed to count the duplicate types but as my table shows there are subtypes which I want to add a field to indicate.
I did this manually but I'm sure it could be done automatically in the query.

CountOfPIT TYPE	PIT TYPE	LENGTH	WIDTH	PIT SUB-TYPE
2	BANDAGE JOINT	0	0
67	EDCM CGP	900	600
5	EDCM CGP (H)	900	1200	a
1	EDCM CGP (H)	900	1300	b
7	EXISTING
4	GP	900	600	a
10	GP	1000	750	b
1	GP (H)	1000	1400	a
1	GP (H)	1300	3000	b
1	GP (H)	1500	750	c
1	GP (H)	1500	1500	d
1	GP (H)	2000	750	e
19	GSEP	1000	750
30	HCC FGP	900	600
41	HW			a
1	HW	1000	800	b
2	JP			a
3	JP	750	750	b
23	JP	1000	750	c
1	JP (H)	1000	1200	a
1	JP (H)	1000	2100	b
1	JP (H)	1100	1600	c
1	JP (H)	1500	750	d
1	JP (H)	1500	2800	e
1	JP (H)	1600	750	f
1	JP (H)	1700	1800	h
1	JP (H)	1900	3000	i
1	JP (H)	4000	1000	j
1	JP (H)	5645	3475	k
1	PIPE CONNECTION			a
3	PIPE CONNECTION	0	0	b
262	SEP	1000	750	a
1	SEP	1500	750	b
1	SEP (H)	1000	900	a
1	SEP (H)	1000	1000	b
4	SEP (H)	1000	1200	c
6	SEP (H)	1000	1400	d
6	SEP (H)	1000	1500	e
2	SEP (H)	1000	2500	f
2	SEP (H)	1000	3000	g
1	SEP (H)	1200	750	h
2	SEP (H)	1400	1400	i
2	SEP (H)	1500	750	j
1	SEP (H)	1500	1500	k
1	SEP (H)	1600	750	l
2	SEP (H)	1700	750	m
1	SEP (H)	2400	1200	n

[orange]

Stevie,
First, welcome to the forum.
How about giving the 30,000 ft overview of the subject matter? Readers in general have no idea of your environment or the business involved. There are some guessers/wizards on the forum that will guess well and give you an answer.

What is the business involved? What is a pit? and subpit? Do you have tables that you are using to support the business and your post? Often better to use simple English and provide an overview along the lines of addressing who, what, where, when, how much and how often.
Good luck.