How can we share with someone a signed record of seeing them, revealing our gratitude such that they can see and appreciate the recognition but without making it fully public?
Declare an "Event" about an "agent", with a "description" of what happened. Technically: Event by Bio Vocabulary
Other possibilities include:
"WatchAction" by schema.org is meant for watching media (eg. a movie).
"Observation" by the W3c Sensor Ontology is close but meant for mechanical devices,
"Witness" by the Library of Congress is for voices in media
Unfortunately, most of the other "observe" actions at LOV are no longer active.
Soon we'll allow for encrypted content, so that only the recipient will be able to see the statement.
Note that the open nature of this service allows for negative expressions as well; that feedback is usually more appropriate in different channels. Someday we hope to provide ways for individuals to filter such things, but for now we simply recognize that there are infinite ways abuse others and we won't proactively shut down channels, prefering to allow freedom until the problem arises.