A sliding loop of rope or chain by which a running yard or gaff is connected to, while still being able to move vertically along, the mast.

装于帆桁中央两侧的索具：能滑动的绳圈或链子，用来把帆桁或缆索拴在船桅上，使之仍可以随意升降。

youdao

The interface is entirely text and music-based -- musicians, if you can call them that, scan an instrument name on the page before sliding over to the notes, which can be played back at different pitches by moving the reader vertically along the line.

ENGADGET: Gocen optical music recognition can read a printed score, play notes in real-time (hands-on video)