The intent of this document is to provide an overview of step 2 of the labelling process of ICOS ocean stations. Section 2 of this document summarises the core variables for each of the station categories: Ship of Opportunity Program (SOOP lines), Repeat Ocean Sections (ROS), Fixed Ocean Stations (FOS), and Marine Flux Towers (MFT). This station type distinction will be maintained throughout the document. Section 3 of this document summarises the required documents to be submitted to the ICOS Ocean Thematic Centre (OTC) by each station’s Principal Investigator (PI) in order to be evaluated for step 2 labelling. Unless otherwise directed by the OTC, only stations that have successfully completed step 1 labelling should provide this information. Furthermore, in section 3, links to excel spreadsheets for metadata information are included, and these must also be completed in order to proceed through step 2 labelling. Section 4 summarises the general processing by the OTC of the 4 to 6 months of raw field data required from the PIs for step 2 labelling.