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

<div id="eq:0">

  ------------------------------------------------------------------------------------------------------------------------ ------------
                                                         $$ this $$                                                             $$(1)$$
  ------------------------------------------------------------------------------------------------------------------------ ------------

</div>

Some equations might be inside of text,

<div id="eq:1">

  ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------------------
                                                                                        $$ for example $$                                                                                                    $$(2)$$
  ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------------------

</div>

this one.

Some equations might be on start of paragraphs:

<div id="eq:2">

  ---------------------------------------------------------------------------------------------------------------------------------- -------------
                                                             $$ start $$                                                                   $$(3)$$
  ---------------------------------------------------------------------------------------------------------------------------------- -------------

</div>

of paragraph.

Other might be on separate paragraphs of their own:

<div id="eq:3">

  ---------------------------------------------------------------------------------------------------------------------------------------------------------------- ----------------
                                                                           $$ separate $$                                                                                   $$(4)$$
  ---------------------------------------------------------------------------------------------------------------------------------------------------------------- ----------------

</div>

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