Generally, if changes are classified minor and do not require a change to the certificate, any method to inform EASA is accepted. This notification should be sent to etsoa [at] easa [dot] europa [dot] eu. It is required to regularly inform EASA about minor changes (at least once per year). The notification can be performed by either providing a summary of changes or the full descriptions of changes.
However, even if no changes had been performed on the ETSO article(s) EASA shall be notified at least once per year that no changes had been performed.
When changes involve a modification to the ETSO authorization, then it is necessary to submit an application through EASA Form 34. The minor change shall be entered in section 3.1 of Form 34.