1. A method for automatically synchronizing production data of a source system and a target system, where a source data worksheet represents a logical organization of a source repository of production data managed by the source system, a target data worksheet represents a logical organization of a target repository of production data managed by the target system, a record of the source data worksheet describes a logical source data element comprised by the logical organization of the source repository, a record of the target data worksheet describes a logical target data element comprised by the logical organization of the target repository, and a first synchronization rule of the set of synchronizations rules instructs a processor of a computer system how to resolve a first inconsistency between the logical source data element and the logical target data element, the method comprising: a processor of a computer system generating a source-to-rule mapping worksheet, where a first record of the source-to-rule mapping worksheet associates the logical source data element with the first synchronization rule; the processor creating an extrinsic data-to-rule mapping worksheet, where a record of the extrinsic data-to-rule mapping worksheet is capable of associating an extrinsic data element with the first synchronization rule, where the extrinsic data element is comprised by neither the source repository nor the target repository, where the record of the extrinsic data-to-rule mapping worksheet associates the extrinsic data element with the first synchronization rule, where the extrinsic data element comprises a distinct element of data associated with an external information source, where the external information source is distinct from any component of the source system, the target system, the source repository, and the target repository, and where the logical procedure of the first synchronization rule depends upon a value of the extrinsic data element; the processor producing a target-to-rule mapping worksheet, where a record of the target-to-rule mapping worksheet associates the logical target data element with the first synchronization rule; the processor constructing a rule-logic worksheet, where a record of the rule-logic worksheet associates the first synchronization rule with a logical procedure by which the processor may resolve the first inconsistency; and the processor automatically responding to a revision to a first revised record of a first worksheet by automatically revising a second revised record of a second worksheet, where the first worksheet is distinct from the second worksheet, the first worksheet and the second worksheet are selected from the group consisting of the source data worksheet, the target data worksheet, the source-to-rule mapping worksheet, the extrinsic data-to-rule mapping worksheet, the target-to-rule mapping worksheet, and the rule-logic worksheet, and where the automatically revising is performed by means of a linkage between the first revised record and the second revised record.