filter (properties)

Description

In Regina 6.0.1 and earlier, the filter element was used to store different types of normal surface filters, and was held within an enclosing packet (surface filter) element. This page describes how the filter element was structured when storing a property filter. Since Regina 7.0, each filter type now has its own XML element, which also serves as the XML element for the filter packet. In particular, property filters are now stored using the filterprop element.

A property filter filters normal surfaces by examining basic topological properties such as orientability and Euler characteristic.

The specific constraints imposed by this filter are specified by its child XML elements. If this filter has several child elements, a surface must satisfy all of the corresponding constraints in order to be accepted by this filter.

More information about surface filters can be found in the general filter element documentation.