I'd say that phrase means 'consideration' in some cases, and in any case something like 'reasonable expectation', which would enter into the 'meeting of minds' prerequisite of contract law.

Banana republics like almost all countries with Civil Law rather than Common Law? And also, you know, some US states and the UCC?

The doctrine that anything not explicit is meaningless in contract law is also referred to as 'the four corners' referring to where you look to interpret the contract; this is considerably relaxed in many jurisdictions (and some situations in the US) where there is considerable information asymmetry and/or power imbalance between parties. With employment contracts in particular; to be a good coder for instance, why would you need to know how dilution of options works? Only to avoid being mislead by your prospective employer?

Conversely, in Civil Law jurisdictions, you see that corporations (rather than employees/consumers and sometimes small businesses) are mostly held to the four corners of the contract as they are professional parties that have legal departments and should be presumed to do their due diligence.