Did a project for consolidating address representations across systems for large logistics a couple years ago. It was the one project where XML was a genuinely adequate representation. Ie you could have a text line address preserving sequence, newlines, and whitespace, yet markup postcode and other distinguished fields. Like

    <line>Bla Ltd</line>
    <line><houseno>11</houseno>, Xyz-Street</line>
    <line><postcode>12345</postcode> MyCity</line>

Taking advantage if the fact that almost all addresses can be written in a line-oriented fashion. Actual addresses were using the much more granular UPU S1 vocabulary. SGML would've been even better since it can treat newlines and whitespace as markup, eliminating <line> boilerplate and just use a regular text block representation.