This function retrieves information about attributes defined in a grid. The attribute list is returned as a string with each attribute name separated by commas. 
            Note: See STRSPLIT to separate the attribute list.
            Examples
            In this example, we retrieve information about the attributes defined in a grid structure: 
            nattr = EOS_GD_INQATTRS(gridID, attrlist)
            Syntax
            Result = EOS_GD_INQATTRS( gridID, attrlist [, LENGTH=variable] )
            Return Value 
            Number of attributes found or (–1) if failure.
            Arguments
            gridID
            Grid id (long) returned by EOS_GD_CREATE or EOS_GD_ATTACH.
            attrlist
            A named variable that will contain the attribute list (string) with entries separated by commas.
            Keywords
            LENGTH
            Set this keyword to a named variable that will contain the length of the attribute list as a long integer.
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