angles

5reg

angles

An angle structure list packet

Content Model
    angles ::= (&xml-struct;*, &xml-spanstrict;?, &xml-spantaut;?,
                &xml-tag;*,
                &packetsyn1;
                &packetsyn2;
                &packetsyn3;
                &packetsyn4;
                &packetsyn5;*)
Attributes
Name | Type
`algorithm` | `NUMBER` (required)
`tautonly` | `CDATA` (required)
`tri` | `CDATA` (required)
&packetattrlist2col;

&eltaddedver;7.0

## Description

This represents an angle structure list packet, one of the many types of packet that together form the packet tree that a user sees when they open a ®ina; data file.

An angle structure list stores a list of angle structures on a particular 3-manifold triangulation. Generally this list will contain the vertex structures whose convex span is the set of all angle structures on the triangulation, though other lists (such as all taut angle structures, or other customised lists) can be stored also.

Since ®ina; 7.0, an angle structure list no longer needs to be a child packet of its underlying triangulation. Instead, the triangulation is denoted by the `tri` attribute. This must be the ID of a 3-dimensional triangulation packet that appears before this list in the packet tree, with respect to a pre-order depth-first traversal (i.e., the triangulation must appear before this list in the &xml; data file). The triangulation may be an anonymous packet (see &xml-anon;).

The individual angle structures in this list are contained in the child &xml-struct; elements. Since ®ina; 7.0, the parameters of the angle structure enumeration that created this list are stored in the attributes; there is no longer a child &xml-angleparams; element.

&packetchilddesc;

### Parents

&packetparents;

### Children

The following elements occur in `angles`, and are specific to the angle structure list packet type:

- &xml-spanstrict;
- &xml-spantaut;
- &xml-struct;

. &packetchildren;

## Attributes

The following attributes are specific to angle structure lists:

`algorithm`

- Specifies the algorithm that was used to enumerate these angle structures.

  This must be an integer, formed as a bitwise OR combination of constants from the `AngleAlg` enumeration in ®ina;'s calculation engine.

  An example of such an integer might be 32, which represents the constant `AngleAlg::DD`.

  ®ina; versions 6.0.1 and earlier did not store this information in its data files at all. If it is not provided, it will be treated as `AngleAlg::Legacy`.

`tautonly`

- Either `T` if only taut structures are enumerated, or `F` if all vertex angle structures are enumerated.

  ®ina; versions 4.6 and earlier did not store this information in its data files at all. If it not provided through either this attribute or a (deprecated) child &xml-angleparams; element, it will be treated as `F` (since taut enumeration was not offered in those very old versions of ®ina;).

`tri`

- The ID of the triangulation on which these angle structures lie. This must match the `id` attribute of a 3-dimensional triangulation that appears before this list in a pre-order depth-first traversal of the full packet tree.

&packetattrdesc;