DAN is capable of using pre-existing files (i.e. files that existed
before the invocation of DAN) in expressions, provided the data
conforms to one of the formats described in the User's Manual and
under the `ASCII_input' topic.

Pre-existing files may be either text files or binary files.  Text
files are created using DAN's editor, your system text editor, the
WRITE procedure, or one of your application programs.
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Assignment statements create temporary binary files, and these files
can be made permanent by the SAVE procedure.  The format for binary
files is described in the User's Manual and, for C programmers, in the
`datarec.h' file on the distribution disk.  The `store_data' routine
(also on the distribution disk in both C source code and compiled
object module format) may be used in your application program to
generate DAN compatible binary files.

The READ function must be used to input text files, while binary files
may be used directly in any DAN expression.  A text file may be input
and the resulting values used to create a temporary binary file.  The
binary file may then be used as a term in subsequent expressions.  This
method is usually more efficient if the binary file is used in multiple
expressions.
