While I’m reading about markup language in Wikipedia, I came across this:
In modern word-processing systems, presentational markup is often saved in descriptive-markup-oriented systems such as XML, and then processed procedurally by implementations.
I couldn’t understand what that exactly means. A brief explanation would be helpful.
“Presentational” and “descriptive” are mainly just slogans with vague meaning. XML follows the tradition of SGML (Standard Generalized Markup Language) in the sense of being generalized markup, in contrast with previous markup systems, which were command-like, or procedural instructions on formatting. Generalized markup is a general concept: it allows procedural markup, other presentational markup, and descriptive markup.
The point is that XML (like SGML) as such is agnostic as regards to the meaning of markup, It is pure syntax, designed to be easily processable. Thus, it can easily be used to store and carry information like formatting information. For example, modern versions of Microsoft Office use an XML-based format, which is mostly used just for formatting, though with some markup carying structural or logical information.
