Remove certain part of string based on value from other column

[Nurzh_17]

Hello all, 

I have issue with removing certain part of string value in my column. 

Example: 

Table "Document"

DocumentNumber	DocumentSourceCategory
61-2300-B-PID-2350-01	Master Document
61-2300-B-PID-2350-01-07812	Project Working Copy
61-2300-B-PID-2350-01-07917D	Project Working Copy
61-2300-B-PID-2350-01-07917	Project Working Copy
61-2300-B-PID-2350-01-14398	Project Working Copy
61-2300-B-PID-2350-01-00209	Project Working Copy
61-2300-B-PID-2350-01-07812-21	Project Working Copy
61-2300-B-PID-2350-01-05209D	Project Working Copy
61-2300-B-PID-2350-01-07812-21D1	Project Working Copy
61-2300-B-PID-2350-01-05908	Project Working Copy
61-2300-B-PID-2350-01-07812D	Project Working Copy
61-2300-B-PID-2350-01-05209	Project Working Copy
61-2300-B-PID-2350-01-03210D	Project Working Copy
61-2300-B-PID-2350-01-07812-21P	Project Working Copy
61-2300-B-PID-2350-01-07812-21D	Project Working Copy
61-2300-B-PID-2350-01-03210	Project Working Copy

Desired New Column that will identify us the Master Document Number of this copies: 

DocumentNumber	DocumentSourceCategory	Document cut
61-2300-B-PID-2350-01	Master Document	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-07812	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-07917D	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-07917	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-14398	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-00209	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-07812-21	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-05209D	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-07812-21D1	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-05908	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-07812D	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-05209	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-03210D	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-07812-21P	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-07812-21D	Project Working Copy	61-2300-B-PID-2350-01
61-2300-B-PID-2350-01-03210	Project Working Copy	61-2300-B-PID-2350-01

Thank you!

[some_bih]

Hi @Nurzh_17 one possible solution could be to create new column in Power query using M function Text.Start

(I recognize pattern from your picture: first 21 character should retrive):

New column Document cut code is

= Table.AddColumn(#"Promoted Headers", "Document cut", each Text.Start([DocumentNumber],21))

I hope this help