MarkerShape:
    | "arrowUp"
    | "arrowDown"
    | "circle"
    | "square"
    | "triangleUp"
    | "triangleDown"
    | "diamond"
    | "flag"
    | "text"
    | "labelUp"
    | "labelDown"

labelUp / labelDown are text plates with a tail, for named signals ("Buy", "Sell") rather than bare glyphs. The tail points at the anchor price and the body sits clear of it: labelUp's tail points up so its body hangs below the anchor, labelDown is the mirror. Both require text.