IFAC License agreement
“Subsequent derivative publication may be based on the already published IFAC conference article, but must in itself satisfy all the requirements of an original contribution to the literature, as prescribed by the journal to which the paper is submitted. A submission which simply constitutes only in minor modifications of the IFAC conference article is a form of self-plagiarism, which is not acceptable. At a minimum, the journal paper must explain the contribution of the conference paper, and describe the distinguishing additional contribution made in the journal paper. All submitted papers will undergo the normal review process of the corresponding journal.
Whenever a derivative journal publication does eventuate then this journal paper must contain an appropriate reference to the already published IFAC-PapersOnLine publication, preferably using the DOI attribute.”