The interest in channel models in which the data is sent as an unordered set
of binary strings has increased lately, due to emerging applications in DNA
storage, among others. In this paper we analyze the minimal redundancy of
binary codes for this channel under substitution errors, and provide several
constructions, some of which are shown to be asymptotically optimal up to
constants. The surprising result in this paper is that while the information
vector is sliced into a set of unordered strings, the amount of redundant bits
that are required to correct errors is order-wise equivalent to the amount
required in the classical error correcting paradigm