Fields are usually presented to users in main listing tables and on add/edit forms,
or used for various control structures in each controller.
pseudo_value statement provides a way to use 'pseudo' columns for these various purposes.
The definition of a pseudo column is a complex query/field that is not actually part of the table itself,
but has been given an alias so that it can be treated as if it were.
To see an example, build:
bigtop -c example.bigtop all
Change to the newly created PhoneProv directory and look in PhoneProv/lib/PhoneProv/GEN/E911.pm and PhoneProv/lib/PhoneProv/GEN/DirectoryInfo.pm for 'days_until_install'.