Bear in mind the following limitations when you're setting up click and impression tags:

• A placement ID can only occur within one site and one campaign for search platforms.
• An ad set ID can only occur within one campaign.
• You can have up to 100,000 campaigns per platform at this time.
• A tag can only contain alphanumeric and ASCII characters (%, $, {}, [], (), <>, _, ., :, !, #, -, ~, A-Z, a-z, 0-9).
• URL parameters must be shorter than 1,024 characters.

Learn more about preparing tags.

* Nguồn: Facebook