<P> Additional descriptive information about the image should be contained in the image description on the image's page . </P> <P> Several types of images warrant special treatment: </P> <Ul> <Li> Periodic table snippets for each element--no caption needed </Li> <Li> Infobox images with mission insignia--no caption needed, but if there is a description of the symbolism, it should be included on the image description page </Li> <Li> Other images (especially within infoboxes) where the purpose of the image is clearly nominative, that is, that the picture serves as the typical example of the subject of the article and offers no further information--no caption needed . </Li> <Li> Chemical compound diagrams (as in TNT) could benefit from a mention of the role of the structure in the properties of the compound . </Li> <Li> Group portraits of a few people (presumably related to the article) should list the names of the individuals so that readers can identify individuals . Larger groups should have an index photo with numbered silhouettes and a key listing each person's name . </Li> <Li> When portraits of a person in an article about that person are captioned, they should be captioned with the year . For example, if the photo is of a special occasion, or of historical significance such as Wernher von Braun surrendering to the Americans, the caption should follow the usual style . </Li> </Ul> <Li> Periodic table snippets for each element--no caption needed </Li>

Why would an author include an image and caption in an informational text