3.4.2.2.2 Explicit Naming.

Symbols which have the form location.item receive their values from a source described by location and item. Symbols of the form inputs.port derive their values from the input port with the name port. For example, a symbol inputs.time receives its value from the input port named time. A result of a preceding tool can explicitly be addressed by the pattern tool-label.result-label which identifies the result result-label of the tool tool-label. The symbols aux.symbol and env.variable identify auxiliary symbols of the simulation-flow-model, or environment variables, respectively.

Each of the naming schemes has advantages and disadvantages. Although explicit naming is very strict, it might be inconvenient if a tool is temporarily skipped and instead of its results, those of its predecessor should be taken. In this situation, implicit naming would be superior to explicit naming. On the other hand, implicit naming could introduce ambiguities which are very hard to find. For example, one could think of a tool that uses a result labeled file of a preceding tool. For some reason, the user might decide to introduce a new input port file while, at the same time, he/she is not aware of the existence of a tool which is accessed via implicit naming. As a result, implicit naming identifies the newly defined input port as the source for the symbol's value instead of the desired result of the preceding tool. An explicit symbol name of the form mytool.file avoids such ambiguities.