It specifies the root directory of a relative path file or a remote file.
When the main directory is not specified, there are three types of cases for executing a cellset file in esProc designer:
If the current .splx/.dfx file is saved, the main directory is the directory where the file exists;
If the current .splx/.dfx file isn’t saved, the main directory is the directory where the last used file is stored;
If the current .splx/.dfx file isn’t saved and it’s the first time a file has been used, the main directory is the [installation directory]\esProc\bin.