If a hidden card does not include the word 'here', can it target anything on any battlefield, or is it restricted to its location?

Ruling: When a card is played as hidden, it automatically gains "here" as a targeting restriction, limiting its valid targets to only the battlefield where it is hidden.

Sequence:

1. Card is played hidden on a battlefield
2. Card automatically gains "here" restriction
3. When revealed/activated, it can only target units/entities on that same battlefield

Nuances:

• Hidden Zhonya moves to base after being revealed because gear cannot be attached to a battlefield
• Tideturner can target outside its location due to its "when play" trigger