Question: How to fix "Error, `||` unexpected"?

Execute the following codes in Maple input (1-D math) in the Standard interface. 


Then an error occurred. But if one copy them into 2-D math (instead of Convert To>2-D Math Input) and execute them directly, everything goes without any error messages.

It says that mixed 1-D and 2-D math inside one command is not supported and not recommended stylistically. However, I just want to understand the reason why an error is raised here. 



`Maple 2022.2, X86 64 WINDOWS, Oct 23 2022, Build ID 1657361`



`Standard Worksheet Interface, Maple 2022.2, Windows 10, October 23 2022 Build ID 1657361`



Error, `||` unexpected


cat("A" .. "C"), cat("d" .. "f") || '`$`("G" .. "I"), `$`("j" .. "l")'

"AG", "AH", "AI", "Aj", "Ak", "Al", "BG", "BH", "BI", "Bj", "Bk", "Bl", "CG", "CH", "CI", "Cj", "Ck", "Cl", "dG", "dH", "dI", "dj", "dk", "dl", "eG", "eH", "eI", "ej", "ek", "el", "fG", "fH", "fI", "fj", "fk", "fl"



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