JSTL if tag for equal strings
I think the other answers miss one important detail regarding the property name to use in the EL expression. The rules for converting from the method names to property names are specified in 'Introspector.decpitalize` which is part of the java bean standard:
This normally means converting the first character from upper case to lower case, but in the (unusual) special case when there is more than one character and both the first and second characters are upper case, we leave it alone.
Thus "FooBah" becomes "fooBah" and "X" becomes "x", but "URL" stays as "URL".
So in your case the JSTL code should look like the following, note the capital 'P':
<c:if test = "${ansokanInfo.PSystem == 'NAT'}">