ORIGINAL: el cid again
There is a real difference between an Independent Infantry Brigade and an Independent Mixed Brigade:
Yes, indeed!
ORIGINAL: el cid again
Fundamentally an IMB is an augmented regimental combat team, with a full battalion of organic artillery, an engineer unit, a signal unit, and often a tank unit, as well as a proper slice of what we call support. It can divide, but normally functions as a single unit, and it can be assigned offensive missions.
Fundamentally, an IIB is a set of independent battalion combat teams, each with a company of light guns, a platoon of signals, a platoon of engineers, and its own support company. It is these latter that formed into Class C divisions - by giving two of them a HQ element and little else - not the IMBs. It can be in one place, but virtually always is divided into four or five parts, stationed too far apart to be mutually supporting - and it never is assigned offensive missions against major field formations.
Now that said, I will repeat: IJA is complex. Only the PLA of today is MORE complex (and remarkably similar). It is possible to find exceptions to any rule - and it is almost impossible to make any general statement that is true because there are so many exceptions! So I sympathize that different interpretations may exist. The nature of written Japanese is such it is easy to get lost in your own assumptions (it is normal to only IMPLY the subject of a sentence - guess wrong and you misread the writer). Further, if Kanji are used, there are AT LEAST four (and my ex CIA software often produces TWELVE) different possible meanings!
The IMBs certainly varied alot, but for most of them their equipment and composition is known.
The C-Type divisions were formed from the same Independent Battalions, artillery units and engineer units that were part of the IMBs that formed them and the IMBs were redesignated Independent Brigades afterwards (as part of the C-Divisions; in most cases the IMBs supplied five battalions and three new battalions were newly raised to get the full complement of eight battalions = two brigades with four battalions each).