IDA Help: Binary string format

It is possible to enter a sequence of the following items:
  - a number in the selected radix (hexadecimal, decimal or octal)
  - a string constant: "string"
  - a Unicode string constant: L"unicode string"
  - a question mark '?' to ignore variable bytes

The sequence must be separated by a space or a comma.

An entered number will occupy the minimal number of bytes it fits in
with the restriction that the number of bytes is a power of 2 (1, 2, or 4 bytes).

Two question marks without a space between them are the same as one question mark.
One question mark corresponds to one CPU byte. One CPU byte may consist of
multiple octets for a wide-byte CPU, like TMS320C28.

Example:
  CD 21          - bytes 0xCD, 0x21
  21CD           - bytes 0xCD, 0x21 (the order depends on the endiannes)
  "Hello", 0     - the null terminated string "Hello"
  L"Hello"       - 'H', 0, 'e', 0, 'l', 0, 'l', 0, 'o', 0
  B8 ? ? ? ? 90  - byte 0xB8, 4 bytes with any value, byte 0x90