Feature Request

I'd like to request a feature for Gantt charts in PlantUML to support custom week numbering, starting from the project start date.

Current Behavior

Currently, printscale weekly displays ISO calendar weeks, but there is no option to start numbering from week 1 at the project start.

Expected Behavior

It would be helpful to have a syntax like:

Or even better, an option like:

Use Case

When managing a project timeline, it’s often more intuitive to number weeks relative to the project start (e.g., "Week 1", "Week 2", etc.), especially in agile or short-term projects.

Thank you for your great work!