How to express a letter pattern similar to LLLLL.com

[gwkg]

I'm starting a blog to analyze the LLLLL.com market and need some opinions.

How would one express the following pattern of letters in an LLLLL domain with only 2 letters. For example:

BAAAB.com
CAAAC.com
DAAAD.com
AEEEA.com

or

SSDDD.com
SSXXX.com
SSLLL.com
AABBB.com

I was thinking M = Match, but that would only work for one of the matching letters.

All the patterns with A & B in the same domain are reg'd so what do you think about using those letters.

ABBBA = any triple letter wrapped by 2 matching letters
AABBB = any double letter followed by a triple letter
AAABB = any triple letter followed by a double letter

another way would be to use D for double and T for triple

DTTTD, DDTTT, TTTDD

For quadruple letters, would you go back to L for any letter and M for matching?

LMMMM = baaaa, caaaa, daaaa, eaaaa...

When there are static letters, would you express them with lowercase and M for matching letter?

etcMM = etcaa, etcbb, etccc, etcdd...

 

[shockie]

kiss rule: use {a,b} for two letters, and {a,b,c} for three letters.

 

[VURG]

I prefer numbers {1,2,3, etc...} to letters.

 

[gwkg]

So how exactly would you express:

ABBBA
AABBB
BBBAA
ABBBB
AAAAB
ABABA

 

[cassius]

To combine flexibility with simplicity I would do this.

Keep the basic v,c notation.
Add x, y and z to indicate either (people are used to using x, y and z as variables from algebra).

Use caps to indicate matching elements.

So you have things like

XYYYX
VxxxV
VXyXV
VCCCV

The first one would describe strings like cdddc, aiiia, addda etc.
The second one would describe strings like itrsi,atvba etc.
The third one would describe string like atrta, ivovi etc.
The fourth one would describe strings like utttu, orrro, etc.