The theory of applied photography distinguishes the category of so-called Universal photos, which are suitable for multiple documents due to having the same requirements for e.g. poses, but above all the size of the photo. Because the vast majority of photographers sell pictures for documents in sets of 4 or 8 identical shots, it's worth knowing where these can be used, because usually one picture is all you need.
The most common dimensions used for photos are 3 x 4 cm photos . Such photographs are suitable in Malta for such nationwide documents as a passport, a Maltese ID or a driving licence.