The cache is used for CST MICROWAVE STUDIO blocks and Library blocks. Both block types have parameters that set the S-parameters and Impedances to be stored.
The blocks are identified by unique identifiers. The identifier consists of the content of the mod file (MD5 checksum), the number of parameters, the number of ports and modes, and the content of all depended files (like CAD import files).
If you use a network path for your library, the cache can be shared between other instances of CST DESIGN STUDIO™. This is because every parameter set for a block must only be calculated once. The second time a calculation is run, the block results will be found in the cache.
If you change the mod file either by changing the structure or by adding a parameter, a new identifier will be generated and a new cache subfolder will be used. Changing the value of a parameter has, of course, no effects on the cache. Note that if a calculation is aborted, the results are not written to cache, regardless of the accuracy reached to that point.
To prevent the cache from growing infinitely large, CST DESIGN STUDIO™ checks the contents of the cache folder for entries older than 200 days and deletes them.