$ forester init > /dev/null

  $ cat > trees/index.tree << EOF
  > \title{Root}
  > \subtree{
  >   \title{Alpha}
  >   \subtree{\title{Alpha child}}
  > }
  > \transclude{foo}
  > \<div>{\subtree{\title{Wrapped}}}
  > \scope{
  >   \put\transclude/toc{false}
  >   \subtree{\title{Excluded from toc}}
  > }
  > \subtree{\title{Beta}}
  > EOF

  $ cat > trees/foo.tree << EOF
  > \title{Foo}
  > \subtree{\title{Foo child}}
  > EOF

  $ forester build > /dev/null

  $ grep -oE '<div class="mainmatter[^"]*" id="[^"]*"' output/index/index.html | grep -oE 'id="[^"]*"'
  id="id--5b14-2c-2072-29"
  id="id--5b42-2c-2070-29"
  id="id-https-3a-2f-2fwww-2emy-great-forest-2enet-2ffoo-2f"
  id="id--5b13-2c-2039-29"
  id="id--5b98-2c-20122-29"
  id="id--5b164-2c-20198-29"
  id="id--5b202-2c-20223-29"

  $ grep -oE 'data-target="[^"]*"' output/index/index.html
  data-target="#id--5b14-2c-2072-29"
  data-target="#id--5b42-2c-2070-29"
  data-target="#id-https-3a-2f-2fwww-2emy-great-forest-2enet-2ffoo-2f"
  data-target="#id--5b13-2c-2039-29"
  data-target="#id--5b98-2c-20122-29"
  data-target="#id--5b202-2c-20223-29"

Only one entry since it only appears in the mainmatter, not the toc:

  $ grep -c 'Excluded from toc' output/index/index.html
  1