AMA Manual of Style - Stacy L. Christiansen, Cheryl Iverson 2020

Online-Only (Supplementary) Material
Manuscript Preparation for Submission and Publication

Publishing online-only content permits inclusion of audio, video, and interactive content. In addition, to conserve use of print pages and editorial resources and yet allow interested readers access to supplementary material (eg, additional tables, figures, or references, derivation of complex equations, appendixes, detailed description of methods, trial protocols, large amounts of relevant but detailed data), some journals may publish online-only material to supplement the content that appears in the main article. Each element included in the online supplemental content should be cited in the text of the main manuscript (eg, eTable in the Supplement) and numbered in order of citation in the text (eg, eTable 1, eTable 2, eFigure 1, eFigure 2, eMethods).⁸

The JAMA Network journals offer authors specific guidance on preparing online-only supplements (text, tables, and figures) as well as audio and video files that may be useful for other journals and all authors. See, for example, the section Online-Only Supplements and Multimedia in the JAMA Instructions for Authors at http://jamanetwork.com/journals/jama/pages/instructions-for-authors#SeeOnline-OnlySupplementsandMultimedia.

In the JAMA Network journals, this call-out appears on the first page of the print or PDF version of the article (with a link embedded to the online-only content) and in a prominent navigational link in the online version:

⊞ Supplemental content

⊞ Video

and is called out at the appropriate place in the text:

(eFigure 1 in the Supplement)

(Video)

In addition, many journals, including the JAMA Network journals, post copies of protocols and statistical analysis plans for clinical trials as online supplemental material.

The National Information Standards Organization (NISO), together with the National Federation of Advanced Information Services, has described such online supplementary material as “items essential to the understanding of the work” (ie, “integral”) or “nonessential [to the work]” (ie, “additional”). NISO counsels that “content that is a critical part of the evidence for the article’s conclusions can be lost to future readers if it is indiscriminately grouped with other less crucial materials surrounding the article. Thus, it is important for authors and editors to think carefully about Supplemental Materials.”¹⁴ See NISO’s Recommended Practices for Online Supplemental Journal Article Materials for additional guidance.¹⁴

NISO recommends that “supplemental materials be described (and cited and linked) at the same level as a table or figure that is contained within the article.”¹⁴

It is the policy of the JAMA Network journals that online supplemental content is published under the imprimatur of the journal and so should undergo editorial evaluation. However, this content may not be edited or formatted and may be posted as submitted by the authors. For example, the JAMA Network journals publish the following disclaimer with supplementary online content:

This supplementary material has been provided by the authors to give readers additional information about their work.