...there are still some relics around: old CVS tags. For instance, in org/drools/conflict/FifoConflictResolver.java we find:

 * @version $Id: RandomConflictResolver.java,v 1.1 2004/06/25 01:55:16 mproctor
 *          Exp $


For the drools repository:

drools[FIX-INF]$ grep -l '@version' $j
./drools-compiler/src/test/java/org/drools/IndexedNumber.java
./drools-core/src/test/java/org/drools/factmodel/InstancesHashcodedTest.java
./drools-core/src/test/java/org/drools/spi/MockObjectType.java
./drools-core/src/main/java/org/drools/RuleIntegrationException.java
./drools-core/src/main/java/org/drools/base/ClassObjectType.java
./drools-core/src/main/java/org/drools/spi/ConflictResolver.java
./drools-core/src/main/java/org/drools/spi/Accumulator.java
./drools-core/src/main/java/org/drools/spi/RuleComponent.java
./drools-core/src/main/java/org/drools/ProcessIntegrationException.java
./drools-core/src/main/java/org/drools/rule/Package.java
./drools-core/src/main/java/org/drools/rule/FixedDuration.java
./drools-core/src/main/java/org/drools/core/util/StringUtils.java
./drools-core/src/main/java/org/drools/core/util/CompositeCollection.java
./drools-core/src/main/java/org/drools/core/util/IteratorChain.java
./drools-core/src/main/java/org/drools/core/util/ArrayUtils.java
./drools-core/src/main/java/org/drools/core/util/ArrayIterator.java
./drools-core/src/main/java/org/drools/common/AbstractRuleBase.java
./drools-core/src/main/java/org/drools/common/InstanceEqualsConstraint.java
./drools-core/src/main/java/org/drools/conflict/AbstractConflictResolver.java
./drools-core/src/main/java/org/drools/conflict/TotalRecencyConflictResolver.java
./drools-core/src/main/java/org/drools/conflict/FifoConflictResolver.java
./drools-core/src/main/java/org/drools/conflict/ComplexityConflictResolver.java
./drools-core/src/main/java/org/drools/conflict/SimplicityConflictResolver.java
./drools-core/src/main/java/org/drools/conflict/SalienceConflictResolver.java
./drools-core/src/main/java/org/drools/conflict/LifoConflictResolver.java
./drools-core/src/main/java/org/drools/conflict/RandomConflictResolver.java
./drools-core/src/main/java/org/drools/conflict/LoadOrderConflictResolver.java
./drools-core/src/main/java/org/drools/util/codec/StringUtils.java
./drools-core/src/main/java/org/drools/util/codec/Base64.java
./drools-core/src/main/java/org/drools/util/codec/CharEncoding.java
./drools-core/src/main/java/org/drools/reteoo/AccumulateNode.java
./drools-core/src/main/java/org/drools/reteoo/ReteooRuleBase.java
./drools-jsr94/src/test/java/org/drools/jsr94/rules/repository/RuleExecutionSetRepositoryLoaderTest.java
./drools-jsr94/src/test/java/org/drools/jsr94/rules/repository/TestRuleExecutionSetRepository.java
./drools-jsr94/src/main/java/org/drools/jsr94/rules/repository/RuleExecutionSetRepositoryLoader.java
./drools-jsr94/src/main/java/org/drools/jsr94/rules/repository/RuleExecutionSetRepositoryException.java