What is MaxBTC and what it represents? I am trying to understand what is the phrase "MaxBTC" and for what is it used? I am new to bitcoins.

Thank you very much.
"We can represent any bitcoin account with MaxBTC 251."


It appears that MaxBTC is used here as a strict upper bound to refer to maximum number of bitcoins that will ever exist.

There will always be fewer than 21m bitcoins. All of Bitcoin's protocol logic actually is defined in terms of satoshis. There are 100 million satoshis per bitcoin. Altogether, this means that there will be fewer than 2,100,000,000,000,000 or 2.1×1015 satoshis.

Therefore, 251, which is about 2.25×1015, is larger than the total satoshis that will ever exist in the Bitcoin protocol and thus big enough to express any single amount of bitcoin that will ever need to be referenced.