Regular Expression for matching spreadsheet cells with A1 notation

spreadsheet cell regular expression

^(?:(?'startcolumn'[A-Za-z]{1,3})(?'startrow'\d{1,7}):(?'endcolumn'[A-Za-z]{1,3})(?'endrow'\d{1,7}))$|^(?:(?'startcolumn'[A-Za-z]{1,3}):(?'endcolumn'[A-Za-z]{1,3}))$|^(?:(?'startcolumn'[A-Za-z]{1,3})(?'startrow'\d{1,7}))$|^(?:(?'startcolumn'[A-Za-z]{1,3})(?'startrow'\d{1,7}):(?'endcolumn'[A-Za-z]{1,3}))$|^(?:(?'startcolumn'[A-Za-z]{1,3})(?'startrow'\d{1,7}):(?'endrow'\d{1,7}))$|^(?:(?'startcolumn'[A-Za-z]{1,3}):(?'endcolumn'[A-Za-z]{1,3})(?'endrow'\d{1,7}))$|^(?:(?'startrow'\d{1,7}):(?'endrow'\d{1,7}))$|^(?:(?'startrow'\d{1,7}):(?'endcolumn'[A-Za-z]{1,3})(?'endrow'\d{1,7}))$

Uses overlapping named capture groups so it only works with in C# with .NET's regex engine.
This is actually 8 regular expressions OR'd together, each one identifying a different format.
A1:B2
A:B
A1
A1:B
A1:2
A:B2
1:2
1:B2