Question on intervals in VALUE-statement

[Syntas_error]

I copied this code of a practice question, the question is that value will be assigned to 10, which is seemingly between the "warm" and "hot" temperature ranges.

proc format lib=sasuser;
value tempc low< 0 = 'BELOW FREEZING'
0 < 5 = 'COLD'
5 < 10 = 'MILD'
10 < 15 = 'WARM'
15 < high = 'HOT';
run;

Intuitively, it seems that 10 is assigned no format and should be presented just as 10. But not only does the key claim 10 will be presented as "WARM", the code refuses to run on my system! 

SAS tells me the "<" signts is not recognized and will be ignored(!).

So:

Question 1:

Why on earth would 10 be presented as 'WARM' and not as 10, is this another typo?

Question 2:

Why does the code fail to run? I double checked with the advanced programmer's prep guide and this seems to be the way to assign a format to an interval....  

asdf

[Jagadishkatam · Accepted solution]

The syntax of the code was incorrect , the correct syntax is as below

We create the formats to change the display of the data, if you just want to display the values as is then do not apply the format. The format controls the display of the data.

proc format lib=sasuser;
value tempc low -< 0 = 'BELOW FREEZING'
0 -< 5 = 'COLD'
5 -< 10 = 'MILD'
10 -< 15 = 'WARM'
15 - high = 'HOT';
run;

[Syntas_error]

So in summary:

1. We have to use the "-<"-sign instead of the ""<"-sign when specifying intervals. 

2. Forr some unknown reason we can't use an "-<"-sign before "high" but must use the "-"-sign instead?

[Jagadishkatam]

Yes I agree with your understanding.
When we use the words like low or high, it is implicit they refer to lower or higher values hence we do not need the '<' symbol.