"The original name SEQUEL, which is widely regarded as a pun on QUEL, the query language of Ingres,[14] was later changed to SQL (dropping the vowels) because "SEQUEL" was a trademark of the UK-based Hawker Siddeley Dynamics Engineering Limited company.[15] The label SQL later became the acronym for Structured Query Language."
"The original name SEQUEL, which is widely regarded as a pun on QUEL, the query language of Ingres,[14] was later changed to SQL (dropping the vowels) because "SEQUEL" was a trademark of the UK-based Hawker Siddeley Dynamics Engineering Limited company.[15] The label SQL later became the acronym for Structured Query Language."
https://en.wikipedia.org/wiki/SQL
Indeed, reading through the paper, I think it's too similar to modern SQL to be considered a different language.