In a footnote to the data, the source explained:

Remark: the Luxembourg retail trade turnover index for January 2015 and the subsequent months has been revised as a result of restructuring operations in the internet sales activity branch of the Luxembourg retail trade sector. These restructurings will also have an impact on other statistics.

In response, we have synchronized values in Data Buffet. We have not appended a notation to the series metadata, because this is not a definitional break. This impacts four pairs of reported NSA series (at current and constant prices) and our SA supplements.

The impacted series reside in the historical catalog (Luxembourg » Consumer » Retail turnover index) and include, for example: 

• WRI47UM.ILUX    = Retail trade; except of motor vehicles and motorcycles [47], (Index 2010 =100, NSA)
• WRI4719UM.ILUX  = Other retail sale in non-specialized stores [47.19]
• WRIX473UM.ILUX  = Retail sale excluding fuel [47 ex. 47.3]
• WRJROTHRUM.ILUX = Other retail trade [47.7 to 47.9], (Vol. Index 2010=100, NSA)

Because catalog locations are subject to change, the upper-right search box on DataBuffet.com provides a "find in catalog" mode that accepts a mnemonic.