variable definitions

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1

Hi,
I’m new at natural enviroment and i’m reading Programming Guide (Version 8.2.5 May 2015) manual.
At this manual it’s said in one example that

1 #INT1 (I1) /* Integer, 1 byte.
1 #INT2 (I2) /* Integer, 2 bytes.
1 #INT3 (I3) /* Invalid definition!!!
1 #INT4 (I4) /* Integer, 4 bytes.
1 #INT5 (I5) /* Invalid definition!!!
1 #FLT4 (F4) /* Floating point, 4 bytes.
1 #FLT8 (F8) /* Floating point, 8 bytes.
1 #FLT2 (F2) /* Invalid definition!!!
1 #DATE (D) /* Date (internal format/

I don’t understand the invalid definitions … Why are they invalid?
Maybe it’s a nousense question but I would wellcome an explanation

thanks

2

CPU hardware has arithmetic instructions for integers of length 1, 2, or 4. Neither hardware nor software (operating system, compiler, etc) support other lengths.