Undocumented features.

These features are all poorly documented.

<base>
Inserts a comment into the document. Must not contain any tags nested within it. Comments do not affect the flow of text.
Earlier versions of mosaic will recognise the following as a comment.
```
<! comment body  >
```
<br>
breaks the line
and carries on to the next line.
<form>.....</form>
Put together collections of
```
inputs

 
```
<hr>
Places a horizontal line between the lines of text.
<input NAME=name [value=string] [Type =type] [SIZE=x,y] [checked] ALIGN=align>
Input fields
<option [value="text"] [selected]>
is used within <SELECT>.
<strike>
It "~~strikes out~~" the selected text