Contemplating supporting Markdown syntax

http://daringfireball.net/projects/markdown/syntax#list
Implementations
    https://sourceforge.net/p/forge/documentation/markdown_syntax/
    http://stackoverflow.com/editing-help
    https://help.github.com/articles/markdown-basics + https://help.github.com/articles/github-flavored-markdown


Operator to specify my customization values
<!-- keyword: value -->  Like stackoverflow.com's syntax highlighting operation
:::metadata   Like Sourceforge's code language specifier
[[macroname attr1=val1 attr2=val2]]  Used generally on Sourceforge


Perhaps biggest diff from Creole is that <html> is generally permitted.
Markdown text is scanned for angle brackets of HTML tags, and they are not escaped.
# not for lists nor for <tt>.

There are conflicting differences between
    https://help.github.com/articles/github-flavored-markdown
and
    http://stackoverflow.com/editing-help
E.g. syntax highlighting
    ```ruby
    ...
    ```
vs.
    <!-- language*: * -->

Biggest diff for GFM format is that internal newlines are significant.
For regular, end line with "  " to generate a <br />.

Sourceforg eonly has [TOC] for the obivious purpose.

Sourceforge only has [[include ref=SamplePage]]

List
    List operators must be followed by blank line.  This distinguishes from inlines.
    Must be preceded by a blank line.  Says this, but untrue.  UNTRUE
    Blank lines between items cause items to be <p>-wrapped.
        (How many and where blank lines are required seems unspecified)
    Follow-up paragraphs must begin with 4 spaces
    To embed code or blockquotes, just add 4 spaces before your operator.
    Ident "another" 4 spaces for nested list elements

No way to do non-code pre-formatting.  :(
Looks like Sourceforge Markdown does not assume code.  Need to check what HTML gets created.

Code
    Prefix every line by 4 spaces, which will be subtracted.
    Markdown disabled in here.

Blockquotes are just offset and marked.  No Markdown disabling.

Paired operators must be closed and may not span block elements.

An `inline code` span.  <code> similar to <tt> monospaced font, but also disables Markdown interpretation.

Escaping generally \, but ` escaped with ``.
Check how to escape HTML tags on the others.  Sourceforge requires you to enter character entity codes.

URLs inside of <> to make explicit (for self-labeled).

[implSpecificArtifactLinks]

Tables.  Dashes and pipes and MUST FULLY UNDERSCORE HEADER LINE FIELDS.
No initial pipe.
Header line and underscore line required.

Headers # style generally.  == and -- underscore for h1 and h2.

--- or more for hr.  Must follow a blank line.

[URL label](http://url "Tool tip text")
The URL may just a case-insensitive reference defined elsewhere like:
    [reference]: http://the.url "tool tip"
Image same but preceded by ! Label is used for alt text.
file: URLs don't work, but plain non-URL paths work right.
