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Name

filtercomb — A logical combination surface filter

Synopsis

Content Model 
filtercomb ::= (tag*,
                (container|textdata|script|attachment|
                 tri|link|snappeadata|
                 angles|surfaces|hypersurfaces|
                 filtercomb|filterprop|filtertrivial|
                 anon|anonref)*)
Attributes
NameType
opCDATA (required)
idCDATA
labelCDATA

Added in Regina 7.0

Description

This represents a combination filter packet, one of the many types of packet that together form the packet tree that a user sees when they open a Regina data file, and also one of the different types of filter that users can create to refine a set of normal surfaces.

A combination filter uses a logical operation to combine other normal surface filters into a single more complex surface filter.

The filters being combined must be immediate children of this filter in the packet tree. The logical operation that combines them is stored in the op attribute. (This attribute replaces the deprecated op element, which was used with filter in older versions of Regina.)

There are several child XML elements that are common to all packet types. The tag elements represent an arbitrary set of string “tags” that users can attach to a packet to help organise their data. The remaining child elements list all of Regina's packet types (container, textdata, etc.), and these represent the immediate children of this packet in the packet tree.

Parents

The following elements can contain any packet element (including this): angles, anon, anonref, attachment, container, filtercomb, filterprop, filtertrivial, hypersurfaces, link, regina, script, snappeadata, surfaces, textdata, tri. This list includes all packet types, as well as the top-level element regina.

Children

Element filtercomb has no children that are specific to combination filters.

The following children can occur in all packet elements: angles, anon, anonref, attachment, container, filtercomb, filterprop, filtertrivial, hypersurfaces, link, script, snappeadata, surfaces, tag, textdata, tri. This list includes all packet types, as well as the tag element for tagging individual packets.

Attributes

The following attributes are specific to combination filters:

op

Represents the logical operation used to combine the child filters. This must be either and or or.

The following attributes are common to all packet types:

id

A unique identifier for this packet. Packets are not required to have IDs, but when they are present they must be distinct (i.e., no packets in the same file may share the same ID). IDs do not need to be human-readable, must not contain leading or trailing whitespace, and must not be empty strings. Currently, IDs are built from base 64 hashes of the underlying C++ pointers.

The purpose of these packet IDs is to allow other packets to reference this packet (for instance, so that a script packet can store references to its variables).

IDs are not required to stay the same across subsequent loads and saves of the same file. In other words, if you load a file and save it again, the packet IDs are allowed to change.

label

The name given by the user to this particular packet within the overall packet tree.

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