More on FILENAME and INFILE
The FILENAME statement assigns a fileref to the long name used by the system. The general syntax is as follows.

FILENAME statement FILENAME fileref 'system-file-name'; fileref is any valid SAS name. system-file-name is the name of the file, as defined by the particular operating system being used.

SAS works under a large number of operating systems, all with different naming conventions.
Directory based systems
VAX:

FILENAME EXAMPLE1 'UD:[Best.BIS524]Example 1.dat';

DOS or Windows:

FILENAME EXAMPLE1 'C:\BIS524\Example1.dat';

Macintosh OS:

FILENAME EXAMPLE1 'Hard disk:BIS 524:Data files:Example 1';

UNIX:

FILENAME EXAMPLE1 '/home/albest/BIS524/Example1.dat';

IBM mainframe systems
OS/390 batch:

FILENAME EXAMPLE1 'best.BIS524.datafile.example1';

For a complete definition of file naming conventions in your environment, see the operating system documentation and consult the "SAS Companion for xxx Environment."