Electronic shelf label glossary

An electronic shelf label is a shelf-edge display whose price changes from a central system. This glossary collects the terms that come up when you evaluate, buy or install one, in short definitions with a link to the page that covers each topic in depth. Every term has its own anchor so it can be cited.

Hardware and display

ESL (Electronic Shelf Label) {#esl}

A shelf display with a radio and a battery that shows an item’s price and other data and updates without anyone touching it. It replaces the paper price tag. The guide to electronic shelf labels explains the whole system.

E-paper (electronic ink) {#e-paper}

A bistable display technology: it keeps the image with no power and only draws energy when it changes. That is why nearly all labels use it, and why battery life is counted in years rather than weeks. See the entry on electronic ink.

LCD {#lcd}

Liquid crystal display. Unlike e-paper it needs power to hold the image, so it consumes more and is kept for cases that need fast refresh or more brightness. The first LCD labels used segments, which render some letters poorly.

BWR / BWRY {#bwr-bwry}

The colours an e-paper screen supports: black, white and red (BWR), or black, white, red and yellow (BWRY). Colour helps highlight promotions, but a colour refresh takes longer than a black-and-white one. The comparisons show which models from each manufacturer offer which option.

Gateway / access point {#gateway}

The device that links the store network to the labels’ radio. It receives price changes from the software and broadcasts them to the labels in its area. How many you need depends on floor area and metal obstacles such as shelving and freezers, not only on the label count. Some vendors call it a base station.

NFC {#nfc}

Near-field communication, working over a few centimetres. On a label it is used to link the label to an item with a phone, or to let a shopper open a product page by tapping. It does not replace the radio that updates the price.

OTA (Over-The-Air) {#ota}

Updating the firmware of a label or gateway by radio, without taking the unit down. It cuts store visits, but ask every vendor what can be updated, in which window, and how a failed update is rolled back.

Product and price data

SKU {#sku}

The internal code a company uses to identify an item in its inventory. It belongs to each retailer: two chains may name the same product differently. The label is linked to the SKU, and the SKU in turn points to the GTIN.

EAN / GTIN {#ean-gtin}

GTIN is the trade item number administered by GS1, with 8, 12, 13 or 14 digits. EAN-13 is the barcode normally used to print a 13-digit GTIN, which is why the two terms are used almost interchangeably. The GTIN is usually what gets scanned to pair a label with its item.

Prior price (reference price) {#prior-price}

The previous price shown when a discount is announced. In the EU, the Omnibus Directive (2019/2161) amended the Price Indication Directive so that an announced price reduction must state the prior price, defined as the lowest price applied during a period of at least 30 days before the reduction. It applies from 28 May 2022 and member states set the details, so national rules differ. A label that shows “was/now” must keep that price history. The UK is outside this EU rule; check current UK guidance separately.

Unit price {#unit-price}

The final price, taxes included, per kilogram, litre, metre or other unit of measurement, shown next to the selling price. In the EU this stems from Directive 98/6/EC; in the UK it is required by the Price Marking Order 2004 (article 5), with exemptions, for example where the unit price equals the selling price. On a small label, making both prices readable is a design problem as much as a compliance one.

Dynamic pricing {#dynamic-pricing}

Changing a product’s price by rule: time of day, stock level, expiry date, demand or competitor prices. With paper tags it is impractical; with electronic labels the limit becomes commercial policy rather than logistics. It is also where transparency with the shopper and the prior price matter, when the change is a reduction.

Store operations

Planogram {#planogram}

A diagram showing which product goes on which shelf, how many facings it takes and in what order. It is the basis for placing labels, because a label belongs to a position on the shelf and not only to an item. When the planogram changes, the label has to move.

Out-of-stock {#out-of-stock}

An item is in the catalogue but there are no units on the shelf. The label does not restock anything, but if the system is connected to inventory it can help spot the gap and flag it on the screen or to staff. The guide covers the use cases.

Pick-to-light {#pick-to-light}

An order-picking method in which a light shows the exact location of the item to collect. Some labels carry an LED that can do this job in stores that fulfil online orders; not all of them include one.

Screens and advertising

Digital signage {#digital-signage}

Screens, usually LCD or LED, that show video or branded content and campaigns in store. It is distinct from the price label, although both can coexist in one store. Here we only define the term. Keonex, which publishes this site, sells digital signage on keonex.com and, for pharmacies, through FarmaConnect.

Retail media {#retail-media}

Selling advertising space inside the store, physical or online, to the brands the retailer stocks. In a physical store the space can be a screen, a display or the label itself. It is a revenue line for the retailer, not a function of the label, and it requires measuring audience and conversion.

How to use this glossary

For the long definition of a concept, start with the main guide; to put a figure on a project, use the TCO calculator. If a term is missing, the glossary grows in instalments and each new term is added with its source. How we work and who is behind the site is explained in the methodology.