State and Certainty

If the place does not exist any more, then you need to specify when it existed with a state element

<state type="existence" from="0410" to="0605">
        <certainty locus="value" match="@from" notAfter="0410"></certainty>
        <certainty locus="value" match="@to" notBefore="0605"></certainty>
    </state>

The following is also perfectly fine, and perhaps preferable, stating without further precision that the place is attested in one of the main periodizations, in this example Aksumite

<state type="existence" ref="Aks"></state>

the ref points to an Authority list file Aks.xml which contains the permalink to the PeriodO definition, in this case, http://n2t.net/ark:/99152/p03tcss4qvv.

if this is an attested place only in one source, note down that as well in @source or in a <desc>↗ or <note>↗. In the example below, we found in Smith's Dictionary of Greek and Roman Geography the passage in Ptolemy where the port of the Adulitae is mentioned and we have added a note about it linking to the <bibl>↗ element as its source. The <note>↗ has also a @cRef to point to the exact passage in Perseus.

example:

<listBibl>
...
<bibl xml:id="Smith">
               <ptr target="bm:SmithGreekRomanGeo"></ptr>
               <citedRange unit="item">s.v. Adu&apos;le or Adu&apos;lis</citedRange>
            </bibl>
            </listBibl>
               <note></note>

               <note source="#Smith"><ref cRef="http://data.perseus.org/citations/urn:cts:greekLit:tlg0363.tlg007.perseus-grc1:4.7">Ptolemy 4.7.8</ref></note>