Changing radio selection to checkboxes - trying to use split()

Hi everyone:
I have succesfully been using the following code in my templates to view a specific page selected in the panel by a radio button.

<?php foreach ($privatePages = $pages->children()->filterby('category', 'sectionOne') as $artwork): ?>

However, now I need to change the radio selection to checkboxes, so the record can be seen on mulitple pages, and cannot understand how to use split() in the template. (Or even if I am supposed to use split() at all) -

My blueprint gives the desired checkboxes in the panel. (I changed ‘category’ to ‘categories’)

                label: Sections
                type: checkboxes
                  home: home
                  sectionOne: Section One
                  sectionTwo: Section Two

I then changed ‘category’ to ‘categories’ in my template and tried to put split() somewhwere but failed miserably - blank pages, errors, etc…

Thank you in advance for any help

To use a comma separated value, pass the separator as last argument:

filterby('category', 'sectionOne', ',')

Brilliant! Thank you so much. All working perfectly.