WRITE3()operations) such as ID-referenced, vertical profile, and sparse matrix, it is legal for the number of variables to be zero. Variable-names should begin with an (upper or lower case) alphabetic character which may be followed by alphabetic, numeric, or or the underscore character _. Case is significant. (netCDF also permits the "minus" and "period" characters; however, these break the construction of algebraic formulas, etc., in PAVE and other analysis and visualization packages, and should not be used.)
Names, units-designations, and text descriptions are stored in the
file-headers and may be accessed via the
FDESC data structures after
a call to
DESC3(). The reverse
procedure is used to create new files: store the file's description in
the FDESC data structures, and then call
For C programmers: The
gdnam, upnam, execn, fdesc, updsc, vname,
blank-padded character arrays (padded to a length of
NAMLEN3=16 for name fields and
description variables), not null-terminated C strings. On the other
hand, file name and variable name arguments to
xtract3c() should be null-terminated C
Fortran::C string-conversion routines fstr2cstr(), name2cstr(), cstr2fstr() are very useful for passing character strings in a mixed-language programming situation.
Within a file, all the variables have the same dimensions, horizontal coordinate system and horizontal grid structure, number of layers and vertical grid structure, time step structure, and type of data structure, although they may have different basic data type.
There are three (or four) kinds of
basic data type which individual variables
may have, as indicated by the following "magic number"
parameters defined in PARMS3.EXT ,
and stored in the
VTYPE3D arrays of
Layers range from 1 to
NLAYS3D is the attribute in
descriptions for the number of layers.
Vertical coordinate and vertical grid descriptions found in
FDESC data structures
fully characterize the layering structure of files, at least
for the standard set of vertical coordinate types.
There are also three kinds of
supported, discriminated on the basis of the time step
and stored according to
Models-3 date and time conventions, and
found in FDESC file descriptions .
These kinds of time step structure are:
There are eight types of data structure currently supported
by the I/O API. Data structure type is indicated by
"magic number" values
FTYPE3D in file descriptions such as those found in
FDESC3.EXT. Definitions for
these magic numbers are found in
PARMS3.EXT . The data types, together with the names of the magic
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