Question

which type of punctuation signals the reader that words have been omitted from a direct quotation?

Answer 1

an ellipsis

Quite often, for succinctness, a writer will omit part of a quotation. To show readers that part of the quotation is missing, a writer should use three dots (like this …). These three dots are called ellipsis. Ellipsis is usually written … or […]. For example:

Original: "I stopped believing in Santa Claus when my mother took me to see him in a department store, and he asked for my autograph." (Shirley Temple)
With ellipsis: "I stopped believing in Santa Claus when…he asked for my autograph."

Original: "A hat should be taken off when you greet a lady and left off for the rest of your life – nothing looks more stupid than a hat."
With ellipsis: "A hat should be taken off when you greet a lady and left off […] nothing looks more stupid than a hat."
Another example:

Jameson promised: "In accordance with the statement, the bank will provide the services...outlined in the brochure."
(The text between services and outlined has been deemed to be irrelevant. However, the three dots (called ellipsis) show the reader that text has been omitted.)

Answer 2

all of the strange symbols are the ... aka ellipsis