From a different thread, Rich has explained I2C better(for me)
"When I2CRead is the only command on the script line the syntax is incorrect. The Unknown command is a little misleading since the command is known, it's just been used incorrectly. Think of it (and any of the other Get commands) as data than as a command. Similar to if you just put "Hello World" on a single script line, it means nothing without another command, or like math commands i.e. $ping / $date these mean nothing without a command such as $variable or Print or IF."
I responded with,
"Really thanks so much @Rich! My primitive understanding is obvious, but since you have been giving your knowledge and experience generously on this forum my own understanding has grown immensely and along with many others. This I2CRead "statement" was not well described in great detail as it is here! "