kernel makefile

[zhaobin xv]

in arch/arm/boot/Makefile:
there is some makefile code:

ifeq ($(CONFIG_ZBOOT_ROM),y)
$(obj)/uImage: LOADADDR=$(CONFIG_ZBOOT_ROM_TEXT)
else
$(obj)/uImage: LOADADDR=$(ZRELADDR)
endif

$(obj)/uImage: STARTADDR=$(LOADADDR)

I can't understand the makefile syntax:$(obj)/uImage: STARTADDR=$(LOADADDR),
I can't find the syntax in GNU make Version 3.82
where can I find the syntax