When I need a marker like this I use a code span, like
`--pause`
``````lua
-- Look for a paragraph
function Para (para)
-- With only one child
if 1 == #para.content then
local child = para.content[1]
-- Which is a code span
if 'Code' == child.type then
-- Ignore it if it has a class .code, i.e. `--pause` is a marker, but
-- `--pause`{.code} is "actual" code.
if child.classes:includes('code') then
return nil
end
-- If it is the marker return some block content
if '--pauae' == child.text then
return whatever()
end
end
end
return nil
end
``````