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Regina data files are saved in an optionally compressed XML format. If a data file is compressed, it can be piped through gunzip to recover the plain text XML.
This reference chapter documents the various XML elements that form
a Regina data file and how they are used. The top-level element
for a modern (third-generation) data file is regina.
Regina's file format has gone through a few major changes over the years:
The third-generation format was introduced in Regina 7.0, and is the format described here. It is an XML-based format whose root element is
regina.The second-generation format was used by Regina versions 3.0–6.0.1, and is described in full detail in the archived documentation from Regina 6.0.1. This is also an XML-based format, but whose root element is
reginadata. Regina can transparently read second-generation data files, and it can also write to them on request.The first-generation format was a binary format used by Regina 2.4 and earlier, and was discontinued in mid-2002. Regina can no longer read or write to it at all.
Regarding international characters: As of Regina version 4.5 (May 2008), all XML data is encoded using UTF-8 (which includes plain ASCII as a subset). In versions 4.4 and earlier, data was encoded in LATIN1 without declaring this explicitly in the XML header; Regina is aware of this, and treats all older data files as LATIN1 when they are loaded.
Table of Contents
- abeliangroup - An abelian group
- angles - An angle structure list packet
- anon - A collection of anonymous packets
- anonref - Moves an anonymous packet into the packet tree
- attachment - An arbitrary file attachment
- code - An arbitrary amount of Python code
- compact - Is a normal surface/hypersurface compact?
- components - The components of a knot/link diagram
- compressingdisc - Does a triangulation contain a compressing disc?
- connected - Is a normal surface connected?
- connections - The connections between crossings in a knot/link diagram
- container - A container packet
- crossings - The individual crossings in a knot/link diagram
- euler - The Euler characteristic of a normal surface
- filtercomb - A logical combination surface filter
- filterprop - A surface filter that uses basic properties
- filtertrivial - A trivial surface filter
- fundgroup - The fundamental group of a triangulation
- group - A group presentation
- H1 - The first homology group of a triangulation
- H1Bdry - The first homology group of the boundary of a triangulation
- H1Rel - The relative first homology group of a triangulation
- H2 - The second homology group of a triangulation
- haken - Does a triangulation represent a Haken 3-manifold?
- handlebody - Does a triangulation represent an orientable handlebody?
- hypersurface - A single normal hypersurface in a 4-manifold triangulation
- hypersurfaces - A normal hypersurface list packet
- irreducible - Does a triangulation represent an irreducible 3-manifold?
- link - A knot/link packet
- orbl - Is a normal surface orientable?
- realbdry - Does a normal surface/hypersurface have real boundary?
- regina - An entire Regina data file
- reln - A relation in a group presentation
- script - A script packet
- simplex - A single top-dimensional simplex in a dim-dimensional triangulation
- snappeadata - A SnapPea triangulation packet
- spanstrict - Does an angle structure list span a strict structure?
- spantaut - Does an angle structure list span a taut structure?
- splitsfce - Does a triangulation have a splitting surface?
- struct - A single angle structure
- surface - A single normal surface in a 3-manifold triangulation
- surfaces - A normal surface list packet
- tag - A user-assigned packet tag
- textdata - A text packet
- threesphere - Does a triangulation represent the 3-sphere?
- tri - A triangulation packet
- twosided - Is a normal surface two-sided?
- txi - Does a triangulation represent the product of the torus with an interval?
- var - A single script variable
- zeroeff - Is a triangulation 0-efficient?
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