Mycomarkup is a formal markup language we are defining here.
Mycomarkup document or simply document is a document written in Mycomarkup. Documents are encoded in UTF-8 and nothing else. Any UTF-8 sequence is a valid document.
Parser is a program that turns Mycomarkup into a different representation, such as AST or a different markup language.
Rendering is the process of parsing a document into a representation that can be displayed to a user. For example, PDF, HTML or even PNG.
Character is a Unicode codepoint that is not a control character, except for space, horizontal tab and line feed characters. When parsing, parsers shall only operate on Mycomarkup characters and ignore the rest.
Block is the structural unit of Mycomarkup. Documents are composed of blocks.
Nesting block is a block that can contain other blocks inside. The number and types of blocks a nesting block can nest might be limited, depending on the block.
Non-nesting block is a block that cannot contain other blocks inside.
More definitions will be introduced when defining blocks.