There are two ways to extend fact sheets manually:
Using XSLT Documents to Extend Fact Sheets: XSLT documents work in conjunction with annotation files. The original, SAP-delivered annotation file remains unchanged.
After having implemented any SAP-sided changes to annotation files, for example, after an upgrade, you must test that the fact sheets you have extended using XSLT are still displayed correctly.
Editing Annotation Files Directly to Extend Fact Sheets: As an alternative, you can directly edit the SAP-delivered annotation file. This method allows for more complex changes.
Do not mix the two methods to change one single fact sheet.