Is it the case that if you receive an FID in the update message, you should use the value even if it is blank?

For instance, in the message below should I read ASKSIZE and NO_SELLERS as 'empty' or use the previous known values? For this exchange the ASK_TONE value of "H" indicates "When there are no quotes or all quotes are cancelled"

<->2019.12.20T13:26:59.916 ### dpl0093.equi ### warn ### (17864): processPayload: Received RIC: 7078.T

Resp Message:

AttribInfo: (none)

RespMsg::Model type: 6 (MarketPrice)

RespMsg::Resp type: 3 (Update)

RespMsg::Resp type num: 0 (INSTRUMENT_UPDATE_UNSPECIFIED)

RespMsg::payload:

__

FieldList:

standard data count = 17

__FieldEntry: ASK 4245.0

FieldEntry: ASKSIZE

FieldEntry: NO_SELLERS __

FieldEntry: ASK_TIME 4:26:59.919

FieldEntry: ASK_TONE "H"

FieldEntry: GV2_FLAG "C"

FieldEntry: ASK_TIM_MS 16019919

FieldEntry: EXCHTM_MSP 16019919257

FieldEntry: BID 4260.0

FieldEntry: BIDSIZE 100

FieldEntry: NO_BUYERS 1

FieldEntry: BID_TIME 4:26:59.919

FieldEntry: BID_TONE " "

FieldEntry: GV1_FLAG " "

FieldEntry: BID_TIM_MS 16019919

FieldEntry: ASK_NZERO 4245.0

FieldEntry: BID_NZERO 4260.0