Candace, thank you for the question.
An abbreviated function name, like the “log” in your examples, with a subscript must have a blank cell following the end of the subscript.
See Nemeth Code section 79.d, esp. the second sentence and including example (3) and also section 77.iii including example (8).
The Nemeth Code 1972 Revision WITH UPDATES (that can be found on the Nemeth page of BANA’s website) is the latest Nemeth Code for math and science.
For further discussion, you may also check Lesson 14 of the Provisional Revised Nemeth Course Manual (esp. sections 14.2 and 14.9).
Does that answer your questions? Do you now have follow-up questions? ☺️