tCCD_L vs tCCD_S exploits bank groups. Bursting reads across different bank groups yields higher bandwidth.
One of the most interesting aspects detailed in the 4D revision is the formalization of the feature. In previous generations, the command bus was somewhat "trusted." But as speeds increased, the likelihood of signal integrity issues on the command and address lines grew. jesd79-4d pdf
From reviewing -D against actual failure modes seen in the field: tCCD_L vs tCCD_S exploits bank groups
The standard defines requirements for JEDEC-compliant devices ranging from 2 Gb to 16 Gb . In previous generations, the command bus was somewhat
The document you're asking about, "JESD79-4D PDF," relates to a particular iteration of the JEDEC standard for "DDR SDRAM" (Double Data Rate Synchronous Dynamic Random-Access Memory) Specification. Here's a general overview based on what such a document might entail: