<<wikitext-example src:"There is a block id that is invisible, but you can find it using developer tool's inspect element feature. ^BlockLevelLinksID1">>
# Don't forget the space between the end of the line and the `^`.
# And there is no space between `^` and the id.
# ID should be a [ext[valid HTML element ID|https://developer.mozilla.org/docs/Web/HTML/Global_attributes/id]], to avoid inadvertent errors, only ASCII letters, digits, '_', and '-' should be used, and the value for an id attribute should start with a letter.
And this block id widget will be rendered as an invisible element: