Here are all of the reference naming commands:

1. \thmrdef{name} Use this for all theorem-like objects: theorems, lemmas, propositions, corollaries, definitions and examples. The "name'' may include spaces and punctuation. The tag "thm:'' used in the example is not required, but we recommend using such a tag to minimize the danger that the same name will be used for two different objects. (Note well: the macros do not check for multiply defined names. With a good operating system, you can write a script that will check this after the source has been processed.) The reference \xrefn{name} produces the chapter number followed by the section number followed by the object number, separated by periods, as in the example.

2. \chaprdef{name} Use this for chapters and appendices. The reference \xrefn{name} produces the chapter number or the appendix letter.

3. \secrdef{name} Use this for sections. The reference \xrefn{name} produces the chapter number followed by the section number, separated by a period. You typically should start a section like this:

\section{Description}{}{}
\secrdef{sec:crossrefs}\nobreak 

The \nobreak is needed to make sure the page doesn't end between the section title and the first paragraph of the section. You do not need the \nobreak if you use only the \section macro.

4. \subsecrdef{name} Use this for subsections; \xrefn{name} produces the chapter number followed by the section number and the subsection number, separated by periods. Typical usage:

\subsection{Description}
\subsecrdef{sec:crossrefs}\nobreak 

5. \exrdef{name} Use this for exercises. The reference \xrefn{name} produces the exercise number only—to specify a chapter or section, you must refer to it separately.

6. \figrdef{name} Use this for figures. The reference \xrefn{name} produces the chapter number followed by the figure number, separated by a period.

7. \pagerdef{name} Use this for page numbers.

8. \eqrdef{name} Use this for equation numbers; \xrefn{name} produces the chapter number followed by the section number followed by the equation number, separated by a period. The code

$$\eqalignno{
  2q^2 = p^2 = (2r)^2 = 4r^2 \qquad\hbox{or}\qquad q^2 &= 2r^2.& 
\eqrdef{eq:square root}(\xrefn{eq:square root})\cr
}$$
That was equation number \xrefn{eq:square root}.

produces: $$\eqalignno{ 2q^2 = p^2 = (2r)^2 = 4r^2 \qquad\hbox{or}\qquad q^2 &= 2r^2.& (4.2.1)\cr }$$ That was equation number 4.2.1.