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## Restrictions

There are some restrictions when using XF . Code that is written with XF , or should be imported to XF should consider the following points:

- No variable names starting with xf,
- no window names starting with .xf,
- no procedure names starting with XF,
- no procedure names starting with ShowWindow,
- no procedure names starting with DestroyWindow,
- no procedure names starting with StartupSrc,
- no procedure names starting with MiddleSrc,
- no procedure names starting with EndSrc,
- toplevels may only be children of ``.''.

These restrictions should not affect the normal working with Tcl/Tk . They are needed for design or performance reasons.