If your talking EFB (electronic flight bag) and ATL (
Aircraft
Technical
Log?), then in EASA-land, your best bet would be to chat with your FOI and NAA to see what they ideally are looking for. The ATL would most likely form a Type 'B' software application on the chosen device. Assuming you already have an approval for iPad devices, this would be an approval of the application itself, and inclusion in to your current EFB set-up (Training, Manuals, Policy & Procedures, Audit Schedule, , RA's, Outside Auditing Schedules etc. etc.) - it's a bit of work for sure and not an easy process, and an external agency will likely be able to assist but at a high premium i'm sure (likely 5-figure depending on level of assistance needed!). Also, I would highly recommend contacting the company supplying the software - as if its a dedicated software application, it's highly likely they have a subject matter expert on approvals such as the one i think your looking for, and also will likely hold software conformity certificates, EASA operational evaluation reports, RA's (maybe) etc. - oh, and then there is the Engineering input and required items there that need to be considered, so key to get them on-board and contributing.
https://www.easa.europa.eu/document-...air-operations
The above link takes you to EASA's Easy Access for Air Operations, and all the relevant (current) EDs, AMC's GM, Regs. etc. are all contained within the publication i think you'll find.
If you don't hold an iPad approval, or are about to embark on using a dedicated device that differs from that currently in use, then its basically a new application from the start and then incorporating in to your existing programme alongside the current devices in use IMHO.