The placard is usually a sticker that sits adjacent to, or covering, the dud item or its control. It will be yellow or orange and the person who applies it will write the MEL reference numbers on it. There is a standard ATA numbering system. The MMEL will have this in the index.
Company differences will depend on the Maintenance Manual and local regulations. For example, the MMEL may require one landing light but the local regulation may require both for night flight, or none with a restriction of daylight only etc.
The MEL must be negotiated with your local authority and you will probably have to show equivalent level of safety by some alternative procedure or restriction to get any reduction from the MMEL.