I'm looking for an umbrella term for all the nitty-gritty requirements that it's helpful to have specified up front but which the client never thinks about in his excitement about the product.In the client's mind, they think of the headline requirements, the main user stories such as I need to be able to view the status of all equipment and I need to receive automatically any notification equipment failure. But at times the mundane ones are there but the client never mentions them until the result differs from his unspoken expectations: Well of course a user must be able to change his own password and Of course the user's session must time out after 30 mins Any development team can anticipate what's likely to be needed but is there a name for this category of requirements? Obvious/infrastructural/boring/details? 
What to call requirements that are assumed/invisible/very obvious
requirements;specifications