Prototype variables are names giving an index into a structured block of memory. They are not identical to normal BASIC variables, but may look and act in a very similar manner.

All values are stored byte-aligned, which is efficient with memory, but is a touch slower than word-aligned.

integer%	a 4-byte integer - !index
string$	a 5-byte SIB - $!index
string$[n]	a string in a buffer of length n+1 within the block - $index
string!	an indirected string - $!index
byte?	a 1-byte integer - ?index
float|	a 5-byte floating point number - |index
substr{proto}	a substructure to be created from a previously defined prototype
substr{}	an indirected substructure
array?(n)	an array with n+1 elements
	types ? = % $ ? | !
array#(n)	a bit array with n+1 elements
array?()	an indirected array
	types ? = % $ |
array(n){proto}	an array of n+1 substructures

�	all types of string are read with string$, so the names must differ.
�	strings are terminated by CR(13) when written but will be read when terminated by NULL(0), LF(10) or CR(13); strings should not contain these characters.
�	a buffered string longer than the length of the buffer will be truncated.
�	a substructure is referenced by its name only: substr.
�	a floating point variable must have the '|' suffix.
�	an attempt is made to check that the characters of a variable name comform to BASIC rules, but it cannot be guaranteed.