See the picture from the guitar composition:
What does the apostrophe mean and how does it affect playing ?
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Its more usual use is to indicate where a breath may be taken. Maybe for guitarists short of breath..! Probably a vestige from another transcription of the piece played on a wind instrument. Now more an indication of the end of one phrase, and the beginning of the next, possibly cutting that last crotchet a little bit in length, which is what would happen when played on a wind instrument.