This command pair is identical to <ref cwhil>zonk while</r> except that there is no looping and hence no implicit read. The condition is true providing the expression does not evaluate to NULL. There is no 'else' part but this effect can be achieved by using an if/ifnot pair.
The <lit>ifnot</lit> form simply inverts the 'if' test. Thus an <lit>ifnot</lit> is true if a variable is <i>not</i> defined or you have read all of the values of a dynamic variable. Note that there is no space in 'ifnot' (just to help out the parser a little).
<lit>zonk endif</lit> closes the conditional part whichever form is used.
An indefinite level of nesting is allowed with these commands.
<sh>Example</sh>
<lit><zonk if partyhost>
This week's party is at <zonk tagvalue partyhost>'s house
<zonk endif>
<zonk ifnot partyhost>
There is no party this week :-(
<zonk endif></lit>
Then depending on whether 'partyhost' has a value or not... (I'm sure you can work it out).
