5.5.3. Tagging for Iterative XML Development

Because InDesign does not support schemas (only DTDs), you can't easily control whether people are going to put text, numbers, or dates in a particular manner in your XML elements. In database terms, there isn't anything in InDesign that will enforce "data typing" in the XML that will be valid for doing calculations or other operations. If you accept this limitation, and generally view InDesign as a generator of text content, you will be fine with a database that expects text content in data fields.

If you really need to constrain the contents of an XML element to be a numeric value, a date/time or other data type than text, you will probably not be happy with the InDesign's XML limitations in this regard. Within InDesign itself, the values of XML elements will be treated as text only. If someone types numbers, they are not truly numbers (integer or float) as far as any XML export is concerned.