Service Mappings: Price list Line

Summary:

Hi Team,

I have created one Descriptive Flexfields for on Price item list lines.
this needs to be used as part of pricing calculation in Algorithm.
Would like to know how I can map this value in Service mappings.
In terms of Entities, Sources and services, like whether need to Header or anything related to Pricing Specific.

Enclosed Descriptive Flexfield value for reference in the attached screen shot.

Regards

Prasanth