This is a test file with some referenced equations, line $$ this $$
Some equations might be inside of text, $$ for example $$ this one.
Some equations might be on start of paragraphs:
$$ start $$ of paragraph.
Other might be on separate paragraphs of their own:
$$ separate $$
Some of those can be labelled:
This is a test file with some referenced equations, line
[$$ this \qquad(1)$$]{#eq:0}
Some equations might be inside of text,
[$$ for example \qquad(2)$$]{#eq:1} this one.
Some equations might be on start of paragraphs:
[$$ start \qquad(3)$$]{#eq:2} of paragraph.
Other might be on separate paragraphs of their own:
[$$ separate \qquad(4)$$]{#eq:3}
Then they can be referenced:
Individually eq. 1, eq. 2, eq. 3, eq. 4
Or in groups eqns. 1, 2, 4
Groups will be compacted eqns. 1-4
Unknown references will print labels eqns. **¿eq:none?**, 1, 3, 4
Reference prefix will override default prefix Equation 1, eqns. 3, 4
References with `-` prepended won't have prefix at all: 1, 2, eqns. 3, 4
References with suffix will have suffix printed after index
(configurable): eqns. 1, 2 suffix, 3