I've seen a bunch of names mixed and matched for this so I'm not entirely clear what the correct description is. From what I can tell its most formally Xilinx XACTstep version M1.X, a part of the Alliance CAE series. Earlier documents seem to refer to it as M1.X (ex: M1.3, M1.5) while later documentation simply references to it as Alliance.
The XC2000, XC3000, and XC4000A/D/H families will not be supported by M1.X; only XC3000A and newer families will be supported in the new software. Please note that these families (XC2000, XC3000, and XC4000A/D/H) are being phased out and new designs should not target these devices.
X-BLOX supports the XC4000, XC4000A, XC4000D, XC4000H, XC3000A, XC3000L, and XC3100A FPGA families.
There are some symbols such as DLAT that are available in only the XC2000 and XC5200 families but not in the XC3000 and XC4000 families.