On the main left side Project Menu: Click to open the Project Details.
Click the Task Custom Fields tab.
Ten (10) customizable data fields carry alpha / numeric data at the Project Level.
Attributes added to these Custom Fields can be displayed when viewing the Project Details / Custom Fields.
Custom Field Headings can be added and customized for the Account in Settings/Custom Fiel Headings / Project Custom Field Headings.
These Project Custom data Fields are also available via the API.