This topic describes the file interface concept.
The RFile class represents an individual file and provides
functions required to open, create or replace a file given its name, or to
open a temporary file.
Various Write() functions write data from a binary descriptor,
and Read() functions read data into a binary descriptor.
These functions provide a binary, stream-mode, interface. They are available
in synchronous or asynchronous forms.
The TFileText class provides a record-based text interface
which deals with the details of character-to-byte conversion.
Files may be opened exclusively or shared, and for shared files, a region may be locked.
A file's attributes and directory entry values may be changed while the file is open. The file may also be renamed while it is open.