“Extra” Dimensions
All “degenerate” trailing dimensions of size 1 are eliminated from arrays. Thus, the statements:
A = INTARR(10, 5, 5, 1) 
INFO, A
print the following:
A	 INT = Array(10, 5, 5) 
This removal of superfluous dimensions is usually convenient, but it can cause problems when attempting to write fully general procedures and functions. Therefore, you can specify “extra” dimensions for an array as long as the extra dimensions are all zero. For example, consider a vector defined as:
ARR = INDGEN(10)
The following are all valid references to the 6th element of ARR:
ARR(5) 
ARR(5, 0) 
ARR(5, 0, 0, *, 0) 
Thus, the automatic removal of degenerate trailing dimensions does not cause problems for routines that attempt to access the resulting array.
Subscripting Scalars
References to scalars may be subscripted. All subscripts must be zero. For example:
a = 5 
PRINT, a(0)
a(0) = 6
PRINT, a