Functional Specifications

I have written functional specifications for over seven years. As with design, my primary goal is clarity. To achieve this, I first research the purpose of the specification. In my experience, the parameters differ widely between organizations. In all cases, I make sure that I define all functional behavior including:

Functional conditions (if this, then do that, else this)
Display parameters (if this, then change this display)
Role parameters (who sees this and when)
Confirmation conditions
Error conditions and states
Iteration of every element

OnDemand Software

I added a section to OnDemand specifications that checked features for conformity to section 508 accessibility standards. All of my Specs at OnDemand:

served as a visual reference of the feature's user interface.
provided development requirements for the feature.
included a checklist for the feature's functionality and its potential impact to existing functionality.
provided a reference for quality assurance and testing.
included documentation of the feature for that release.

PRIDE University, for the Pennsylvania Turnpike

In addition to creating the specification document itself, I created step-by-step animations to address maintenance and update procedures. Specifications for PRIDE University:

provided an explanation of the business requirements filled by the site.
specified the Development and Design requirements that the site needed to address.
identified the Development and Design solutions that successfully addressed the business, development, and design requirements.
included comprehensive documentation of how the site was designed and constructed.
provided a reference for maintaining the site.
identified next steps for increasing the site's content scope.

EURO RSCG Worldwide

In addition to the specification documents, I created HTML proof of concepts and a comprehensive style guide to specify application standards. Specifications for EURO:

served as development requirements for the feature, that corresponds one to one with wireframes and HTML prototypes.
provided a reference for quality assurance and testing
included documentation of each feature