|Measures||Accumulators, for use in stages that aggregate.|
|Groups||For defining filters and comparison groups.|
|New Fields||Gaps, rollups, re-basing, unrolling pick vars, and more.|
The two root types of syntax:
<expression>) - This will refer to primitive expressions that are used as the basic building blocks of syntax for field referencing, filter/groups syntax, and the creation of new fields.
Aggregation Function (
<aggregation-function>) - These are special types of expressions only available in certain places to compute metrics by processing multiple records of data. Although an aggregation function may casually (accidentally) be referred to as an expression, one may not use an <aggregation-function> as an <expression>.