The pathname specified when opening or creating a CDF can be any legal pathname for the operating system being used. This includes logical symbols on VMS systems and environment variables on UNIX systems. Trailing blanks are also allowed but will be ignored. This is so Fortran applications do not have to be concerned with the trailing blanks of a Fortran CHARACTER variable. (C character string variables use terminating NUL characters.)
In almost all cases when a CDF pathname is specified, the .cdf
extension should not be appended. (It will be appended automatically
by the CDF library.) The exception to this is when a user has renamed
an existing CDF with a different extension or with no extension (for whatever
reason). When a CDF is opened, the CDF library first appends the .cdf
extension to the pathname specified and then checks to
see if that file exists.
If not, the CDF library will also check to see if a file exists whose
pathname is exactly as specified (without .cdf
appended). If this
is the case, the CDF must be single-file. If the CDF is multi-file, an error
occurs since the CDF library would have no idea as to how the variable files
had been renamed. Note also that the CDF library always appends .cdf
to the pathname specified when creating a CDF.
NOTE:
The CDF toolkit programs will in some cases not recognize a CDF if
it does not have an extension
of .cdf.