Author guidelines in medical journals: Essential rules and rationale.

Instructions for authors issues by editorial offices of scientific journals require periodical critical analysis in order to maintain their clarity and understandability. In this editorial, selected aspects of such guidelines published issued by Advances in Clinical and Experimental Medicine were reappraised by the editors of this journal - regulations concerning financial disclosure and conflict of interest, as well as acknowledgements, equal contribution of 2 or more authors, tables, figures, and references were discussed. Reasons for chosen rules were provided - those which (based on editors' experience and expertise) may not seem obvious to authors - e.g., why equal contribution is permitted, while co-first authorship is not. Multiple examples of papers fulfilling the analyzed rules in a copybook fashion were provided. In Conclusions, it was briefly discussed whether some of the rules specified in instructions for authors could be enforced only after acceptance for publication (e.g., when numeration of tables and figures is concerned or rules regarding acknowledgements). In this section, it was also explained why other rules listed above should be fulfilled before the peer review commences, for 3 reasons: 1) information about funding sources and conflict of interest is crucial for the ethical integrity of the whole work and cannot be added at a later stage; 2) Satisfactory quality of tables and figures is a prerequisite for peer review; 3) Resolving many issues after acceptance would be cumbersome (e.g., reducing the number of tables or figures) or at least significantly extend the time required for editing.