Is there a PORTABLE way of using POSIX_5 file-locking with Ada files: Text_IO Sequential_IO Direct_IO or is one forced to use Posix IO as well? Is there a way of doing this that would be portable just across different Gnat systems? There appears to be nothing relevant in POSIX.SUPPLEMENT_TO_ADA_IO except the comments (in the Florist implementation) that this is a terrible interface! It seems that one needs a way of extracting a Posix File Descriptor from a variable of the appropriate File_Type. No doubt one can do this on any particular implementation by poking around in the System packages and using Unchecked Conversion. BTW there is no intention of mixing Ada IO and POSIX IO on the same open file -- I simply want to lock (portions of) the file before updating it (preferably with Ada IO operations). Alan Barnes Computer Science Telephone: +44 121 359 3611 Ext. 4663 Aston University E-Mail: [log in to unmask] Aston Triangle Fax: +44 121 333 6215 Birmingham B4 7ET WWW: http://www.cs.aston.ac.uk/~barnesa U. K.