Price look-up codes (PLU), produce codes, or produce labels, are identification numbers affixed to produce in grocery stores and supermarkets for inventory purposes. The code may be a four-digit number, ranging from 3000–4999 to identify the type of produce, including the variety of produce.  A “fifth digit” prefix such a ‘9’ identifies an organic produce, and a “fifth digit” prefix of an “8” identifies a genetically modified (GMO) produce.  Jeffrey M. Smith’s article on the Huffington post challenged the idea whether such prefixes can be reliably used to identify an organic from genetically modified produce. However, in July 2012 the International Federation for Produce Standards specified in the produce PLU Codes User’ guide three categories for the fifth prefix digit qualifier. It states that a ‘9’ identifies organic produce, an ‘8’ indicates genetically modified produce, and a ‘0’ or no fifth digit indicates non-qualified produce.