This has been discussed here before years ago. Dan and Deiter sum it up pretty well. I personally view it more like Dieter, a series of drills that were individually called something else many years ago when I first saw them. Put together into the Modern "Tapi-Tapi", they serve as a learning platform to develop particular attributes necessary for stick fighting or self defense. While there is some room for give and take at higher levels, it is decidedly one-sided, that is to say there is usually a driver and a passenger, each able to work on particular skills.
I will preface this remark with a big IN MY OPINION so nobody gets their shorts in a knot:
Professor was genius at distilling difficult concepts into an easy to teach format that travelled well on the seminar circuit. Different people gleaned different degrees of emphasis on his verbiage. Hew would often refer to the same thing differently at different times. Some of this was his language shortcomings (while he spoke many with a high degree of fluency, in english there are subtleties often lost on non native speakers[topic for another discussion])
He would sometimes use a Cebuano term or an Illongo term if English did not come to him in the heat of the moment. People would often hear something called one thing in Chicago and something else in Mass.
In my own limited study of the art, everything interconnects in a meaningful way, so it call all be tapi tapi if that's what you want to call it. The more important thing is taking skill sets, developing attributes, and making some practical use of them for "your art" and your purposes. While this message was lost on a great many, Professor encouraged people to make his art their own. Again, my interpretation, Professor wanted people to practice, refine and build on the concepts themselves which is the highest evolution of the art, whatever label you put on it
