The relevant EBU regulation is 7C which is on page 24 of the Blue Book. This covers opening bids from 2♣ to 3♠ inclusive.
Any of these bids can be used as Multi-type bids and can include any number of meanings that comply with the EBU definition of a strong hand; which is detailed in section 5C3 on page 20 of the Blue Book. This is where the disputed definition of ER25 is located along with definition of "clear cut tricks". Note that this applies to all hands described as strong such as a Precision 1♣.
In addition to the strong meanings a multi-bid can include a single alternative option which is not constrained by any strength requirements.
The options available are:
i) 4+cards in the suit opened
ii) 5+ cards in any named suit
iii) at least 4-4 in two specified suits (this covers Ekren 2♦ for example)
iv) 5+ cards in an unspecified suit (but cannot be the suit opened)
at least 5-4 in two unspecified suits (neither of which can be the suit opened)
SO if you wanted to play 'Benji' without worries you could simply have:
2♣: balanced 19-20 OR any hand with 5+ cards in D/H or S which is likely to make at least 8 tricks OR a strong hand with 5+ clubs which is likely to make game on its own
2♦: balanced 23-24 OR a hand with 5+ clubs which is likely to make 8 tricks OR any strong hand with 5+ cards in D/H or S which is likely to make game on its own
My personal view is that the definition of a strong hand needs looking at and have suggested the following:16 hcp OR 13+ hcp AND 5 or fewer losers according to simple Losing Trick Count (LTC)
(note that LTC is taught to beginners in EBUland)
My definition of my own multis is:
2♣: balanced 23+ OR 16+ hcp with 4 or fewer losers including 5+ hearts OR 8-12 hcp with 6 diamonds
2♦: balanced 20-22 OR 16+ hcp with 4 or fewer losers including 5+ spades OR 5-9 hcp with 6 hearts
Additionally I play 2♥ as showing 3-11 hcp and 4/5 cards in each major which is covered by option iii above.
Please do not carry over any of the 'personal' stuff from the other thread to this one.
Plus... it's free!