Use cases describe the functional requirements for the app. Additional requirements can be categorized as follows.

F Functionality

F001 Import/Load facilities

F002 Usage of colors

F003 Delete functionality

U Useability

U001 Undo/Redo possibility

U002 Reset possibility

U003 Hint/Autosolve possibility

U004 Desktop/Mobile devices

R Reliablility

R001 Autosave possibility

R002 24/7 availability

P Performance

P001  Response within 100ms     

S Supportability

S001 Easy adaptable

S002 Easy extendable