breqn

\begin{dmath}[shiftnumber]
\begin{dmath}[holdnumber]
Holding or shifting the number.
397 \define@key{breqn}{shiftnumber}{\let\eq@shiftnumber\@True}
398 \define@key{breqn}{holdnumber}{\let\eq@holdnumber\@True}
\begin{dmath}[density={.5}]
399 \define@key{breqn}{density}{\def\eq@density@factor{#1}}
\begin{dmath}[indentstep={1em}]
To change the amount of indent for post-initial lines. Note: for lines that begin
with a mathbin symbol there is a fixed amount of indent already built in
(\eqbinoffset) and it cannot be reduced through this option. The indentstep
amount is the indent used for lines that begin with a mathrel symbol.
400 \define@key{breqn}{indentstep}{\eqindentstep#1\relax}
\begin{dmath}[compact]
\begin{dmath}[compact=-2000]
To make mathrels stay inline to the extent possible, use the compact option. Can
give a numeric value in the range −10000 . . . 10000 to adjust the behavior. −10000:
always break at a rel symbol; 10000: never break at a rel symbol.
401 \define@key{breqn}{compact}[-99]{\prerelpenalty=#1\relax}
\begin{dmath}[layout={S}]%
Specify a particular layout. We take care to ensure that \eq@layout ends up
containing one and only one letter.
402 \define@key{breqn}{layout}[?]{%
403 \edef\eq@layout{\@car#1?\@nil}%
404 }
\begin{dmath}[spread={1pt}]
To change the interline spacing in a particular equation.
405 \define@key{breqn}{spread}{%
406 \addtolength\eqlinespacing{#1}%
407 \addtolength\eqlineskip{#1}%
408 \eqlineskiplimit\eqlineskip
409 }
To change the amount of space on the side for “multline” layout.
410 \define@key{breqn}{sidespace}{%
411 \setlength\eq@given@sidespace{#1}%
412 }
\begin{dmath}[style={\small}]
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