Since this report is about open connectivity it might not seem pertinent to review commercial resources. However, a brief review of these is relevant in several contexts. The first aspect to note is that, despite occasional use of the adjective "proprietary" in their descriptions, the primary content of commercial databases is almost entirely derived from open sources. Notwithstanding, they capture, curate, annotate, collate, integrate and index this in valueadded ways (including user-friendly, query front-ends and customer-specific APIs) to justify subscription costs. The second aspect is that by virtue of being able to apply more internal resources than open databases, their statistics indicate where the practical upper limits might lie. The third aspect is that they can give insights into the challenges of extraction, although technical details of how this is done are sparingly presented externally.