How to go about differentiating って meaning [duplicate]

Question

にしかたって字は書けなきゃダメでしょう

(にしかた is a surname)

How do I differentiate whether this って is used to quote "にしかた” or if it is used to act as a topic marker as a replacement for は?

However, in this sentence, a は is already present after 字, so I assume the latter meaning of って does not apply? I heard that using って as a topic marker instead of は is suitable in situations where the speaker is trying to address something being said earlier. Hence, I am pretty confused on which meaning is to be applied.

Besides the two meanings highlighted in the question, is there any other meaning of って I missed out that could justify my question? For now, I understood って can refer to とは, does it also apply to というのは?

Answer 1

にしかたって字は書けなきゃダメでしょう

You differentiate the meaning of って by context. It's hard to see what meaning this sentence could have if it worked as a topic marker here.

So without the first part we have 字は書けなきゃダメでしょう "you have to be able to write characters". Seems like the logical question is, what characters do I have to be able to write? So maybe にしかたって is describing those characters.

So in this case って is an abbreviation of という.

にしかたって字 = にしかたという字 = the characters which say/form/make up にしかた.

Finally, when って is used as a topic marker I believe that it is actually an abbreviation of というのは as you mentioned at the end of your post.