Generally speaking, abbreviations such as sched. or SKDs. (SKDs capitalized is mostly within military/governmental usage) will not appear in prose or similarly written texts. They are reserved for titles, headlines, shorthand notes, or other areas where space is a concern.
The pectoral girdle is an imcomplete ring because it is open in the back between what? The KGB Agent answer: The pectoral girdle is an incomplete ring because it is open in the back between the scapulae.
Gimmal ring. A Gimmal ring with the hoop opened. A gimmal ring, or gimmel ring, is a ring with two or three hoops or links that fit together to form one complete ring. The name gimmal comes from Latin gemellus, twin, via Old French.