BSP2
<BSP
BSP2 is an extended version of BSP29, and by extension BSP30, which expands many format limits, allowing for larger maps. It can store lightmaps as either BSP29-style greyscale or BSP30-style true color. Most modern Quake source ports support BSP2, and the format can be used in GoldSrc by implementing a custom renderer.
ericw-tools can create BSP2-encoded BSPs, but only using Quake or Hexen II clipping hulls and greyscale lightmaps. newbspguy can convert an existing BSP to a true-color BSP2, keeping Half-Life clipping hulls, but this negates the benefits of BSP2.