Where can I find the full DLNA specifications?

The DLNA spec is now available to anyone -- you do not need to be a paying member to download.

From the DLNA.org website: (http://www.dlna.org/dlna-for-industry/guidelines)

Non-member companies may download the Guidelines using the form below.

**Please note that the Guidelines you download today are the most current published version of the DLNA Guidelines. When new Guidelines are released, you will need to download the newer Guidelines to receive the additional updates. Note that not all updates are announced.

Full DLNA specs are available only to DLNA members and dearly paid for. The guy in referenced forum post is mixing things up. UPnP is not a "dlna doc". DLNA is a refinement of UPnP, a set of rules and restrictions in the name of interoperability. A good half of the DLNA specs is just a verbose listing of allowed media formats, subformats, sampling rates, bitrates etc. Whereas UPnP just specifies the abstract device interfaces. The link is correctly http://upnp.org/resources/upnpresources.zip and standardizeddcps is a subfolder there. DCP stands for Device Control Protocol, aka the abstract interface which the device must implement to participate in UPnP network. You would be interested in arch-DeviceArchitecture document to understand UPnP network in general and then MediaServer* folders, most importantly av-ContentDirectory which is a core service to provide DMS per DLNA specification. And yes, Intel Device Spy is absolutely essential tool. Wireshark will be your friend too. Reverse engineering is a daily bread and DLNA specs won't help you :)