HtmlParseMode
Defines the different tokenization content models.
PCData = 0
Initial state: Parsed Character Data (characters will be parsed).
Plaintext = 2
Optional state: Just plain text data (characters will be parsed matching the given ones).
Rawtext = 3
Optional state: Rawtext data (characters will not be parsed).
RCData = 1
Optional state: Raw character data (characters will be parsed from a special table).
Script = 4
Optional state: Script data.