[pmwiki-users] Foxreplace syntax

[Randy]

I have a challenge that seems ripe for Fox's powerful new string  
replacement feature. Unfortunately, I haven't been able to figure out  
the syntax for that feature and I can't find any code examples.

I want to put a form on a page that allows people to check one or more  
groups and one or more pages. The form would look like:

[  ] GroupA
[  ] GroupB

[  ] Page1
[  ] Page2
[  ] Page 3

<Submit>

If someone checks all boxes, I would want output like this to replace  
another section on the page that contains the form:

  |GroupA.Page1 |GroupA.Page2 |GroupA.Page3
  |GroupB,Page1 |GroupB.Page2 |GroupB.Page3

But if the user only checks GroupA, Page1, and Page3, I would want the  
target section to contain:

  |GroupA.Page1 |GroupA.Page3

This would all be easy if the form could restrict output to  
permutations that contain both group and page. If that's possible, I  
don't know how to do it.

In my trials, when the user selects all options, the output is what I  
want. But if the user only selects GroupA, Page1, and Page3, I get:
|GroupA.Page1|GroupA.|GroupA.Page3|
|.Page1 |. |.Page3

I've thought maybe I could use foxreplace to delete any incomplete  
strings to make it look better. But is there an easier way? And if  
not, what is foxreplace's syntax to delete the incomplete strings? And  
can that be done when the user presses submit, so I don't need to put  
a <cleanup> button on the form to fix the results of <submit>?

I hope that makes sense.

Randy