The short answer: 20 (composite score) is the national ACT average. About half of students score above that, and half of students score below. The top 25% of ACT takers score about 24 or more, so if your score is above 24, that's excellent.
1 SavinâNorov machine gun. 2  Space Network, a NASA relay satellite system. 3  Sthene, an obsolete unit of force or thrust in the metre-tonne-second system of units. 4  Substantia nigra, a brain structure. 5  Supernova, a stellar explosion, in astronomy and cosmology.  Tin, a metallic element with chemical symbol Sn.
The Snnn is a code denoting a SYSTEM abend. These codes can be found in the IBM OS/VS Message Library: VS2 System Codes manual. The Ummmm is a code denoting a USER abend. These codes will vary from one user's program to another, therefore these will not be discussed.