Anyway

Eve’s XML and knit­ting ana­logy got me thinking.

You can think of a writ­ten knit­ting pat­tern as being the schema, with a set of instruc­tions, just like the schem­a’s con­tent mod­el. Then each knit­ted item you make that con­forms to that knit­ting pat­tern is like the doc­u­ment instance that con­forms to the schema. Schem­as can be restrict­ive or allow lots of instance struc­ture vari­ations, as can knit­ting pat­terns. And, to tie it into my pre­vi­ous post on knit­ting and copy­right, a schema can be copy­righted (and often is). The ana­logy does have a few prob­lems when you start try­ing to fig­ure out the rela­tion­ship of the set of tags in a doc­u­ment instance and the con­tent with­in those tags; if you think of the knit and purl stitches as being the ele­ments, then the yarn would be the con­tent. Except for, yarn can­’t really be ori­gin­al in the same way as the con­tent in an XML doc­u­ment can be. Some people may dis­agree when it comes to hand-painted yarns, of course.