Hello Tim,
“Uncommitted,” “No Preference,” or “Non Committed Delegate” are actual choices on the ballot in primaries in some states, meaning that the voter votes for a delegate who does not support a particular candidate among the candidates. A way to vote blank or express a voice of protest.
In fact, 13% of votes went into the “uncertified” box in Michigan during the Democratic primary on Tuesday, February 27th. Voters were urged to choose this option after calls from part of the Arab and Muslim community of this state, the country's largest, to express their dissatisfaction with the White House's support for the Israeli offensive in the Gaza Strip.
As the Philadelphia Inquier explains, half of the sixteen states voting this Super Tuesday are offering a “non-binding” option. In the Democratic primaries: Alabama, Colorado, Iowa, Massachusetts, Minnesota, North Carolina and Tennessee. On the Republican side, this is the case in Alabama, Massachusetts, North Carolina, Tennessee and Texas.
Note that Minnesota has a large Muslim minority who, like Michigan, may be tempted to express their disapproval of Biden's stated support for Israel. And in Colorado, where 72 delegates are at stake, the “non-binding” vote could send delegates to the Democratic convention in August if it receives at least 15% of the vote.