Xy-pic User's Guide

## 4.2 Backwards compatibility

The first widely distributed version of Xy-pic was version 2 (from release 1.40 to release 2.6). A special compatibility mode is used automatically if the old style of loading is used (using files named `xypic.tex` and `xypic.sty`). You can also mix old and new diagrams in a document if you load as described in section 1.1 and add the declaration `\xyoption``{v2}`. This provides almost full backwards compatibility: the following are the only known exceptions:

- Automatic "shortening" of arrow tails by `|``<<` break was a bug and has been "fixed" so it does not work any more. Fix: Put a `|``<\hole` break before it as described in section 2.3.
- The release 2.6 `*` position operator is not available. Fix: Use the `:` and `::` operators (described in detail in the reference manual [8]).
- Using as the target of an arrow command does not work. Fix: Enclose it in braces, i.e., write .
- The old `\pit`, `\apit`, and `\bpit` commands are not defined. Fix: Use `*@{>}` (or `\tip`) with variants and rotation.
- The even older notation where an argument in braces to `\rto` and the others was automatically taken to be a "tail" is not supported. Fix: Use the supported `|``<`... notation.

Finally note that sometimes the spacing with version 3.3 is "improved" relative to earlier versions . Please report all other things that do not work the same in version 2.6 and 3.3 to the author.

Xy-pic User's Guide