HOA use of a MSBU

Is anyone familiar with a HOA's use of MSBUs (Municipal Service Benefits Unit)?

I had been researching my neighborhood and had discovered that they had used the county to levy non-ad valorem taxes against the homeowners, in one instance collecting a tax for 8 years and counting, for maintenance of a pond in another subdivision, and most recently, to try and tax the homeowners to build a public facility (I had only recently discovered this through public documents since the HOA had never made mention of this).

I was curious as to whether this is a common practice among certain HOAs.

I was trying to find more information about what one is.

I had learned that my association has apparently applied and had a fund set up to acquire, build, and maintain a public facility. What I thought was strange was that they had decided to use these MSBUs when they have been using their new covenants to collect assessments... I was wondering why a HOA would use a MSBU rather then levying a special assessment, although I would assume it would be easier to get the tax accepted.