Travel Expense Report - Logic Required to Save custom field both as draft and in PR05

[indu_07]

I have a requirement to add a new custom field in Travel Expense page. This will be a text field.

The value entered in this field must get saved in PR05.

Both 'Save as Draft' and 'Save & send for approval' must work and show the data in UI when we open the expense record.

I have so far created the custom field and got it in PR05 screen. Also, I added UI element in view of Webdynpro FITE_VC_GENERAL_DATA.

I want to know how can I save this custom field in SAP and retrieve it. Struggling to get the sample code. In case user exit like EXIT_SAPMP56T_002 has to be used, please provide the logic (preferably sample code) to be written in that.