Paul Koning writes
XML is a nice and flexible interchange format. It usually isn't very efficient but probably efficient enough. It also is very bulky compared to the current format. Again, consider embedded systems. In a system I work on, we can't possibly store the current tzdata format in full, let alone what it would look like if expressed in XML. We solved that by modifying the tz compiler to omit any historic data prior to V1.0, since the nature of this product is that it never has to show times predating its release. With that change, the data fits (it shrinks down to less 200 kbytes, which is acceptable.
Perhaps you missed the point. Your embedded system would not store the XML any more than it now stores the full text distribution with all comments. You now store a compiled form of the distribution text; in the future you would store a compiled form of the XML distribution. I think there are more plusses than minuses in going to XML. Particularly if an XML or RELAX NG schema is also distributed. It would probably be necessary to have a converter from XML back to the current format, but that should not be a problem. ++PLS CONFIDENTIALITY NOTICE: This message contains information which may be confidential or privileged. If you are not the intended recipient, be aware that any disclosure, copying, distribution or use of the contents of this information is prohibited. If you have received this transmission in error, please notify me immediately by telephone.