eStrataHub follows the Land Title and Survey Authority requirement that every Strata Plan number have a 3 letter prefix (the system also accommodates four-character/five-number Federal and First Nations plan numbers). Those generally older properties without numbers must have prefixes added and you can find those prefixes by clicking the "Learn More" link after the "The Strata Plan must have a proper 3 or 4 letter prefix" text.
If you don't know the Strata Plan number, click the link to search by building name. In the pop-up window, start typing the name of the building, and a list of possible candidates will appear. If the one you want appears, click on it, and the Strata Plan field will be filled in for you.