  In High Energy Physics (HEP), analysis metadata comes in many forms -- from
theoretical cross-sections, to calibration corrections, to details about file
processing. Correctly applying metadata is a crucial and often time-consuming
step in an analysis, but designing analysis metadata systems has historically
received little direct attention. Among other considerations, an ideal metadata
tool should be easy to use by new analysers, should scale to large data volumes
and diverse processing paradigms, and should enable future analysis
reinterpretation. This document, which is the product of community discussions
organised by the HEP Software Foundation, categorises types of metadata by
scope and format and gives examples of current metadata solutions. Important
design considerations for metadata systems, including sociological factors,
analysis preservation efforts, and technical factors, are discussed. A list of
best practices and technical requirements for future analysis metadata systems
is presented. These best practices could guide the development of a future
cross-experimental effort for analysis metadata tools.
