When inputting anything other than a letter, number or symbol, an escape? character is inputted instead. For example,

• Backspace is replaced with

  ^H

  and does not delete the preceding character.

• The up, down, right, and left arrow keys are replaced with 

  ^[[A, ^[[B, ^[[C, or ^[[D

  respectively.

• All function keys (F1, F2, etc) are replaced with

  ^[[11~, ^[[12~, etc.

  depending on the key pressed.

• Home, Insert, Delete, End, PgUp, and PgDn are replaced with

  ^[[1~, ^[[2~, etc. 

  respectively.

This only becomes an issue when typos are made and the command needs to be retyped from the beginning without error, as pressing the backspace or delete keys only inserts the matching escape character. This becomes especially annoying when attempting to whitelist players with longer username lengths, especially considering that it is case-sensitive.