Format of a Technical File
There is no specific format for a Technical File required by the EU, however it must contain all relevant information, see Contents of a Technical File Page.
For ease of reading by relevant authorities, it is suggested that PDF format should be used, as this is likely to continue to be able to be read in the future. The file has to be available for at least ten years, more if it is for series machinery, so needs to be able to be read by Authorities, otherwise they may determine it is insufficient.
There is a sample Technical File Index here. Technical File Index
There are a number of software packages available for compiling Technical Files for the Machinery Directive.
COMPLIANCE Risk Software - https://www.compliancerisksoftware.co.uk/ce-marking-machinery-directive/
SafeExpert from IBF - https://www.ibf.at/en/