This ticket captures syntax table (and consequent) changes necessary to support monochrome (4:0:0).

In K1003-v9:

7.3.2.2 Sequence parameter set RBSP syntax:

...
bit_depth_luma_minus8
if( chroma_format_idc != 0 ) <= New condition

bit_depth_chroma_minus8

...
pcm_sample_bit_depth_luma_minus1
if( chroma_format_idc != 0 ) <= New condition

pcm_sample_bit_depth_chroma_minus1

...

7.3.2.3 Picture parameter set RBSP syntax:

...
if( chroma_format_idc != 0 ) { <= New condition

pic_cb_qp_offset
pic_cr_qp_offset
pic_slice_level_chroma_qp_offets_present_flag

} <= New
...

7.3.6 Scaling list data syntax:

...
for( sizeId = 0; sizeId < 4; sizeId++ )

for( matrixId = 0; matrixId < ( sizeId == 3 ) ? 2 : 6; matrixId++ ) {

...
Replace with:
...
for( sizeId = 0; sizeId < 4; sizeId++ ) {

totalMatrices = ( ( chroma_format_idc == 0 )

(sizeId == 3 ) ) ? 2 : 6

for( matrixId = 0; matrixId < totalMatrices; matrixId++ ) {

...
}
...

7.3.8.1 General slice segment header syntax:

...
slice_sao_luma_flag
if( ChromaArrayType != 0 ) <= New condition

slice_sao_chroma_flag

...

7.3.9.3 Sample adaptive offset syntax:

...
for( cIdx = 0; cIdx < 3; cIdx++ ) {
...
Replace with:
...
for( cIdx = 0; cIdx < ( ( ChromaArrayType == 0 ) ? 1 : 3 ); cIdx++ ) {
...

7.3.9.5 Coding unit syntax:

...
if( ChromaArrayType != 0 ) <= New condition

intra_chroma_pred_mode[ x0 ][ y0 ]

...

7.3.9.7 PCM sample syntax:

...

pcm_sample_luma[i]

for( i = 0; i < ( 1 < ( log2CbSize << 1 ) ) >> 1; i++ )

pcm_sample_chroma[i]

...
Replace with:
...

pcm_sample_luma[i]

if( ChromaArrayType != 0 )

for( i = 0; i < ( ( ( 1 << log2CbSize ) / ( SubWidthC * SubHeightC ) ) << 1); i++ )

pcm_sample_chroma[i]

...

7.3.9.8 Transform tree syntax:

...
if( log2TrafoSize > 2 ) {
...
Replace with:
...
if( log2TrafoSize > 2 && ChromaArrayType != 0 ) {
...

7.4.2.3 Picture parameter set RBSP semantics:

...
pic_slice_chroma_qp_offsets_present_flag equal to 1 indicates that the slice_cb_qp_offset and slice_cr_qp_offset syntax elements are present in the associated slice headers. pic_slice_chroma_qp_offsets_present_flag equal to 0 indicates that these syntax elements are not present in the associated slice headers.
...
Replace with:
...
pic_slice_chroma_qp_offsets_present_flag equal to 1 indicates that the slice_cb_qp_offset and slice_cr_qp_offset syntax elements are present in the associated slice headers. pic_slice_chroma_qp_offsets_present_flag equal to 0 indicates that these syntax elements are not present in the associated slice headers. When pic_slice_chroma_qp_offsets_present_flag is not present, it is inferred to be equal to 0.
...