Just lucky it was rope and not piano wire. Heard all kinds of horror stories (some probably urban legends) back in my dirt biking days of things like that. Whenever I encountered an unflagged/unmarked cable, chain, etc. on my rides, I always hung as much stray trailside crap on it as I could find to help make it visible. Which reminds me - - roll of surveyors ribbon should go in my camelbak as standard equipment.