Counted arrays provide the ability to encode variable-length arrays of homogeneous elements. The array is encoded as the element count n (an unsigned integer) followed by the encoding of each of the array's elements, starting with element 0 and progressing through element n- 1. The declaration for variable-length arrays follows this form:
type-name identifier<m>;
or
type-name identifier<>;
The constant m specifies the maximum acceptable element count of an array; if m is not specified, as in the second declaration, it is assumed to be (2**32) - 1.
0 1 2 3
+--+--+--+--+--+--+--+--+--+--+--+--+...+--+--+--+--+
| n | element 0 | element 1 |...|element n-1|
+--+--+--+--+--+--+--+--+--+--+--+--+...+--+--+--+--+
|<-4 bytes->|<--------------n elements------------->|
COUNTED ARRAY
It is an error to encode a value of n that is greater than the maximum described in the specification.