A more thorough explanation:

COMMON-SITUS PICKETING

Common-situs picketing is a type of picketing where a group of people protest outside a workplace or construction site where multiple employers are working. The picketers are not protesting against a specific employer, but rather all of the employers at the site.

For example, if there is a construction site where multiple contractors are working, a union may organize common-situs picketing to protest against all of the contractors for not using union labor. The picketers may hold signs and chant slogans outside the site to try to persuade the contractors to use union labor.

Another example could be a group of workers picketing outside a shopping center where multiple stores are located. The workers may be protesting against all of the stores for not paying fair wages or providing adequate benefits.

Common-situs picketing is a way for workers to protest against multiple employers at once. It is often used by unions to try to persuade employers to use union labor or to improve working conditions. The picketers are not targeting a specific employer, but rather all of the employers at the site. This type of picketing can be effective because it puts pressure on all of the employers to make changes, rather than just one.