You give no information regarding your circumstances (i.e., whether you are currently in employment, have children, are unemployed, etc.) so it makes it harder to define which grant applies to you.
The rate you quote above (€16,748) relates to those on certain social welfare payments who may qualify for a special rate of maintenance grant.
In order to qualify for the ordinary maintenance grant I think your income in the tax year 1 January-31 December 2005 has to be less than €37,365 for you qualify for a full maintenance grant. All of the various income limits are actually set out in Appendix II (a), not in Appendix IV as I mentioned previously.
Unless anyone else can answer specific questions about the scheme, I'd advise you contact your local authority, who administer the scheme in your area.