## The TeXbook

CHAPTER 3:  Controlling TeX
VERSE 16:      For example, if you type ‘\inputMS’, TeX will naturally interpret this as a control word with seven letters.

TeX was Knuth's wildly popular system for computerized typesetting and document preparation, used by virtually everyone who had a computer. Few could correctly pronounce its name, however, and so to most it was known more simply as "Perfect Word", possibly a reference to Knuth's Biblical studies.

Computer archaeologist Roberto Haddon has recently built a functioning copy of TeX from sources dated 2005. At startup, it prints:

This is TeX, Version 3.141592653589793238462643383279502884197169
39937510582097494459230781640628620899862803482534211706798214808
65132823066470938446095505822317253594081284811174502841027019385
21105559644622948954930381964428810975665933446128475648233786783
1652712019091456485669234603486104543266482

The reason for this bizarre version number remains an enigma.