Currently you cannot use relational operators for String fields. e.g. MyFact(name > "bbb")

org.drools.base.evaluators.ComparableEvaluatorsDefinition.evaluators has entries for ValueType.OBJECT_TYPE, but not for ValueType.STRING_TYPE. So it results in DescrBuildError:

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Evaluator '>' does not support type 'ValueType = 'String' : [Rule name='Your First Rule']

Unable to create restriction '[LiteralRestriction: > bbb]' for field 'name' in the rule 'Your First Rule' : [Rule name='Your First Rule']
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According to docs:
4.8.3.1.1.3.1. Operators
"Other relational operatory may be used whenever the type values are ordered;"

http://downloads.jboss.com/drools/docs/5.1.0.34406.FINAL/drools-expert/html_single/index.html#RuleLanguage-ConditionalElements

It is desirable to allow relational operators for String fields as String is Comparable.