h6. [[OS SWI Calls]] h6(. » [[OS_FSControl]] h6((. » OS_FSControl 21 h2. OS_ FSControl 21 h5. (SWI &29) |_<^{width:4em}. Entry | | |<^. R0 |<^. 21 (&15) | |<^. R1 |<^. file handle | |_<^{width:4em}. Exit | | |<^. R0 |<^. Preserved | |<^. R1 |<^. Filing system file handle | |<^. R2 |<^. [[Filing System Information Word|Filing system information word]]| h4. Use The purpose of this call is to return the internal file handle for a filing system. h4. Notes This SWI returns the internal file handle (as returned by [[FSEntry_Open]]) for a given file handle. If the fileswitch handle is invalid R1=0 on return. This SWI should only be used to implement a filing system. h4. See also * [[Filing System Information Word]] * [[OS_FSControl]] * [[FSEntry_Open]]