Filters 
Iroha uses filter-map paradigm to monitor events. Let's look at different types of filters that can be used in Iroha.
Data Filters 
A data filter is a tuple with a single variant, which is a FilterOpt of an EntityFilter:
FilterOpt stands for Optional Filter. It can either AcceptAll or accept BySome of another Filter. An EntityFilter is a filter that matches events produced by a certain type entity, e.g. by account or domain.
Here is the list of EntityFilters in Iroha: