@JeffYoung added a feature that lets you create ERC/DRC errors and warnings from textboxes and fields:
New text variables:
${ERC_WARNING <custom title>}
${ERC_ERROR <custom title>}
${DRC_WARNING <custom title>}
${DRC_ERROR <custom title>}
Variables must be at the start of a field, text item or textbox to be recognised by ERC/DRC.
They resolve to the empty string on the canvas.
