An A320 slat seal at the intersection of the wing and fuselage was discovered missing but because the CDL was not completely read; Maintenance and the Flight Crew did not know this item was required for flight.

Narrative

We had a slat seal that was partially missing at the intersection of the right wing and aircraft fuselage. This was discovered by my copilot during the walk-around. We wrote it up and contacted Maintenance. Maintenance applied the correct CDL procedure and reviewed it with me using a copy of the CDL from their Maintenance Manual. Unfortunately; they only made a copy of the first of a two-sided page and neither I nor they noticed the 'continued' note at the bottom. Because of this we failed to note that this CDL was not allowed to be applied (and deferred) when the slat seal at the meeting of the wing and the fuselage was involved; which was the specific seal we had written-up. My copilot referenced our own onboard Manual while in flight and noted the procedural error. As the aircraft was operating normally and without any problem(s) we notified our Dispatch and Maintenance and continued on to our planned destination (now only less than thirty minutes away). We made a new logbook entry and the slat seal was replaced and signed off before the aircraft was again flown/used.