What is the maximum interception angle for ILS when on radar vectoring? Some time ago when I was designing the approach radar module for the ATC simulator for HCAA, the spec was very clear that the limit had to be placed at 45 degrees. So I took it for granted and I didn't make any research of my own.

But very recently I had a discussion that made me wondering and I couldn't find any online documentation. I found Lnafziger's answer suggesting that


  Controllers may issue a heading or a course direct to a fix between the IF and FAF at intercept angles not greater than 30 degrees for both conventional and RNAV instrument approaches


So I guess this is it for FAA airspace. But I would like to know if there are any EASA regulations or ICAO recommendations that impose 45 degrees in Europe.
45 degrees.

8.9.3.6
Aircraft vectored for final approach should be given a heading or a series of headings calculated to close with the final approach track. The final vector shall enable the aircraft to be established in level flight on the final approach track prior to intercepting the specified or nominal glide path if an MLS, ILS or radar approach is to be made, and should provide an intercept angle with the final approach track of 45 degrees or less.

ICAO Doc 4444 (PANS-ATM)
That said, we very often use a 30 degree intercept angle, even if we are allowed to go up to 45 degrees.