The rEntries and zEntries for a vAttribute and the gEntries for a gAttribute are numbered starting at one (1) for Fortran applications and starting at zero (0) for C applications. For vAttributes the entry numbers are in fact the variable numbers of the variables being described. rEntries correspond to rVariables and zEntries correspond to zVariables. For gAttributes the gEntry numbers have meaning only to the application.
The entry numbers used need not be contiguous (as are variable and attribute numbers). An application may choose to write any combination of entries for a particular attribute (keeping in mind that the entry numbers used for a vAttribute correspond to the existing variables).