System.fmInOut
From RAD Studio VCL Reference
Description
File mode constant used for resetting or rewriting disk files.
fmInOut represents a file mode constant used for resetting or rewriting disk files.
Use the file mode constants when opening and closing disk files. These constants are used primarily in Delphi code, where the Mode field of TFileRec and TTextRec contains one of the file mode constants' values.