The spec (V1005-v1.doc), in section 7.4.7.1, describes the entry
point offsets in relation to tiles_enabled_flag and
entropy_coding_sync_enabled_flag.

For the High Throughput profile family, tiles and entropy coding
sync can be simultaneously selected. The paragraph describing this
particular configuration states:

When tiles_enabled_flag is equal to 1 and
entropy_coding_sync_enabled_flag is equal to 1, each
subset k with k in the range of 0 to num_entry_point_offsets,
inclusive, shall consist of all coded bits of all coding tree
units in the slice segment that include luma coding tree blocks
that are in the same luma coding tree block row of a tile, and
the number of subsets (i.e., the value of
num_entry_point_offsets + 1) shall be equal to the number of
luma coding tree block rows of a tile that contain coding tree
units that are in the coded slice segment.

This implies that only one tile may exist within a slice, which
was not the intention.

It is suggested to change "of a tile" to "of tiles".