On registering each participant obtains a Participant Identification Code (PIC, 9-digit number)  which acts as its unique identifier in the Participant Register. A participant needs to register only  once – the information provided can be further updated or re-used by the participant in other  European Commission's calls for tenders or calls for proposals.   Please provide information about the SME status of the participant in the Participant  Register by filling in the SME Declaration section in the Participant Register. The section  becomes available only when updating/modifying the details of the registered organisation. At any moment during the procurement procedure the Research Executive Agency Validation  Services (hereafter  the EU Validation Services) may contact the participant and ask for  supporting documents on legal existence and status. The requests will be made through the  register's messaging system to the e-mail address of the participant's contact person indicated in  the register. It is the responsibility of the participant to provide a valid e-mail address and to  check it regularly. The documents that may be requested by  the EU Validation Services  are listed  in the EU Grants and Tenders Rules on Legal Entity Validation, LEAR appointment and  Financial Capacity assessment.    Please note that a request for supporting documents by the  EU Validation Services  in no  way implies that the tenderer has been successful.  Economic operators can submit a tender either as a sole tenderer or as a group of tenderers. In  either case subcontracting is permitted. In order to fulfil the selection criteria set out in  Section 3.2 the tenderer can rely on the  capacities of subcontractors or other entities (not subcontractors).  The role of each entity involved in a tender (hereafter referred to as “ involved entity ”) must be  clearly specified in the eSubmission application: i) sole tenderer, ii)  Group leader  of a group of  tenderers, iii) member of a group of tenderers, or iv) subcontractor. For an entity on whose  capacities the tenderer relies to fulfil the selection criteria (that is not a subcontractor), this role is  defined in the commitment letter ( Annex 5.2 ). This applies also where the  involved entities belong to the same economic group.  A joint tender is a situation where a tender is submitted by a group (with or without legal form)  of economic operators regardless of the link they have between them. The group as a whole is  considered a tenderer$^{4}$. $^{4}$ References to  tenderer  or  tenderers  in this document shall be understood as covering both sole tenderers and  groups of economic operators submitting a joint tender.  14 2.4.1. Joint tenders  2.4. Ways to submit a tender: how can economic operators organise themselves to  submit a tender? 