Better document the array key 'pattern' used from hook_theme()

The documentation of the pattern argument does not really make any sense to me.

What I was looking for was this:
How do I actually do something like this in hook_theme (in pseudo-code):

'tmplfamily_[specialization]' = array(
'template' => 'tmplfamily_[specialization]',
...
}

where this should apply automatically to all theme('tmplfamily_[specialization]', $args)
such as
theme('tmplfamily_example1', $args);

which should then invoke tmplfamily_example1.tpl.php

I can't make it work from the documentation, and can't even decide whether 'pattern' would help there or not. The documentation is at least missing a complete working example.