These terms will be encountered when reading the classic 18th and 19th century sailing manuals, and may still be used today when referring to older ships.
Although square sails are mostly worked from the deck, in order to be properly stowed (and released from this stowage) they must be folded by hand and tied to the yard with gaskets.
The ropes are made of either fibre or wire, and are almost always protected from wear by being wormed, parcelled and served, so that the visible outer coating is of tarred thin line.
Once on the yard, modern sailors are able to clip their harnesses onto a safety wire that runs along it (on most ships they will have been unsecured until this point) - in the past, crews enjoyed no such protection.
Modern sailors joining a tall ship are advised to take footwear with a solid sole that will spread the load, rather than the flexible deck shoes and seaboots used on yachts.