4.1.27 ID Quoting

In this section when I refer to a name I mean a variable name, attribute name or a dimension name The allowed characters in a valid netCDF name vary from release to release. (See end section). If you want to use metacharacters in a name or use a method name as a variable name then the name has to be quoted wherever it occurs.

The default NCO name is specified by the regular expressions:

     DGT:     ('0'..'9');
     LPH:     ( 'a'..'z' | 'A'..'Z' | '_' );
     name:    (LPH)(LPH|DGT)+

The first character of a valid name must be alphabetic or the underscore. Any subsequent characters must be alphanumeric or underscore. ( e.g a1,_23, hell_is_666 )

The valid characters in a quoted name are specified by the regular expressions:

     LPHDGT:  ( 'a'..'z' | 'A'..'Z' | '_' | '0'..'9');
     name:    (LPHDGT|'-'|'+'|'.'|'('|')'|':' )+  ;

Quote a variable:
'avg' , '10_+10','set_miss' '+-90field' , '–test'=10.0d

Quote a attribute:
'three@10', 'set_mss@+10', '666@hell', 't1@+units'="kelvin"

Quote a dimension:
'$10', '$t1–', '$–odd', c1['$10','$t1–']=23.0d

     /*
      * ( [a-zA-Z]|[0-9]|'_'|'-'|'+'|'.'|'|':'|'@'|'('|')' )+
      * Verify that a name string is valid
      * CDL syntax, eg, all the characters are
      * alphanumeric, '-', '_', '+', or '.'.
      * Also permit ':', '@', '(', or ')' in names for chemists currently making
      * use of these characters, but don't document until ncgen and ncdump can
      * also handle these characters in names.
      */

netcdf-3.6.3
netcdf-4.0 Final 2008/08/28

     /*
      * Verify that a name string is valid syntax.  The allowed name
      * syntax (in RE form) is:
      *
      * ([a-zA-Z_]|{UTF8})([^\x00-\x1F\x7F/]|{UTF8})*
      *
      * where UTF8 represents a multibyte UTF-8 encoding.  Also, no
      * trailing spaces are permitted in names.  This definition
      * must be consistent with the one in ncgen.l.  We do not allow '/'
      * because HDF5 does not permit slashes in names as slash is used as a
      * group separator.  If UTF-8 is supported, then a multi-byte UTF-8
      * character can occur anywhere within an identifier.  We later
      * normalize UTF-8 strings to NFC to facilitate matching and queries.
      */