How to get a SI or Quotation or any others via custom field

Hi all,

Does anyone knows how to get a document for instance SI instead of using the name field but another custom field?

For example I have

But I need to get from my custom field named TAXFIELD that has value T-FT%202021%2F82

So should be

Thank you and Merry Christmas to all

can you elaborate

Pleas read my post… I have given example of how currently it works and how I would like to work when having a custom field created.