What does «subscribir» mean in Spanish?

To sign at the end or foot of a document.

Examples of use in Spanish: "subscribir un contrato".

"los que abajo subscriben", este uso es incorrecto por tratarse de una redundancia, subscribir ya implica abajo, por lo que debería ser simplemente "los que subscriben".
To agree with one's opinion.

Examples of use in Spanish: "subscribir una opinión".
Subscribing to a newspaper, publication or other service.

Examples of use in Spanish: "subscribirse a una enciclopedia".
To obligate oneself to contribute with others to the payment of an amount.

Examples of use in Spanish: "subscribirse por mil pesos anuales".