Final answer:
Inside index directories, events are stored using keys and values.
Step-by-step explanation:
In index directories, events are stored by using keys and values. The keys are typically the index entries, such as keywords or names, and the values are the corresponding information or data associated with those entries.
For example, in a file system index directory, each file may have a unique key (the file name) and the corresponding value is the file's location or path on the storage device.
In a database index directory, the keys can be column values and the values can be the row identifiers or pointers to the actual data.