I'm having a difficult time using regular expressions in custom
"tags-todo" agenda views.

Is it possible to create custom agenda views using regular expressions,
and if so, do I need to escape certain characters?

I can't get a simple regex like this to work, so I'm suspecting that
I'm doing something wrong or, it's simply not possible to create custom
agenda views that use regular expressions to search for tags.

For example, this expression doesn't even find headings with :projectA:
as a tag

  (setq org-agenda-custom-commands
  '(
     ("1" tags-todo "{projectA}")))

I have the regex surrounded in {} because of the documentation about doing
a tags search - do I need those when using a custom agenda view?

The info page says:
"The second parameter is the search type followed by the string or regular
expression
to be used for the matching" - how do I specify a regular expression versus
a simple
string?

This attempt gives me back a bunch of headings that simply match :project:
but have no
capital A anywhere in the tags.
  (setq org-agenda-custom-commands
  '(
     ("1" tags-todo "project[A]")))

Any help appreciated
Thanks,
--Nate