Read about differences between class and query columns, column types, their properties, system columns, sorting and displaying ObjectGears columns.

Sequences generate a new column value automatically by means of a rising sequence. You can define sequences format according to your needs.

Reference in the column Value from a referenced class can be redirected to a page. You will then display a page with webparts instead of a simple record detail.

Take a look how you can limit data displayed in the selection controls