Perhaps the best way to understand it is to try and replicate it based on the description.
I should have previously mentioned that tone combinations are all reflected in a 00-99 PAO. Since my 00-99 PAO is 52% in a permanent affair with the memdeck I use (Tamariz stack), I sometimes use the same images as playing cards for the tone combinations.
In other words, I can write 34 and think of 4D on the mind map for zhuǎn bèi. Adding the card isn’t always helpful, but sometimes it becomes a ninja star or an ad hoc sweeping tray, etc.
As some will already know, number systems are bi-directional and of great use in language learning if an alphabetical association can’t be found. It’s still an alphabetical association, but just looked at differently.
So in this case, zhuǎn on its own could be 62. Though when I actually memorized zhuǎn bèi I just though of Lac Le Jeune near where I grew up with director Michael Bay making a movie. That was not the best imagine because jeune and zhuǎn didn’t sound the same upon further scrutiny, but it was good enough for the test.
That’s another cool aspect of having a mind map: You can visually work out how associations for sound are going to interact with associations for the tone combinations without having to “see” them in your mind.
It’s faster, more direct and gives the mind a spatial reference similar to a Memory Palace, and all the more so given the use of the hand, which as @LynneKelly recently pointed out in an article, provides a very special level of “encryption.”
Note that I also included Buzan’s 3-color rule in many of the mind maps when I had my colors around. I used to think that idea was kind of strange, but upon reflection, I hypothesize that it probably allows for some diffuse thinking as you’re switching colors, if not a kind of interleaving.
Using a clocklike formation as an additional point of reference is another “hack” because you don’t technically need to see a clock to remember that 12 is north of 6, etc. But I find that it does edge to something more like what I would call a mental picture.