Meaning of Apostrophe in Words Translated to English


What does an apostrophe (') mean in English translations of Japanese words?
For example, an online grammar site says, "When you contract te oku to
t'oku…."

Although just a beginning-level student, I have come across this numerous
times, both online and in English-language books. I do not know how to
determine what kana have been replaced by the apostrophe. Or, perhaps it
represents a brief pause in pronunciation, like that made with doubled
consonant sounds?




The case where the apostrophe is used to avoid ambiguity is already mentioned
in the comments of the question and NattoYum's own answer, but this is not the
case in "t'oku".

As noted by psosuna and others, it means contraction, and the change from "te
oku" to "t'oku" is [音便](https://ja.wikipedia.org/wiki/%E9%9F%B3%E4%BE%BF). I
don't think that is standard in transliterated Japanese however, and I have
seen many grammar sites that introduce this grammar without using the
apostrophe.

