Use of MDEntryRefID in new update messages

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Imported from previous forum

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As it stands, the description of the MDEntryRefID tag states that this item may be included in a message with MDUpdateAction=New(0).

To quote from the draft standard:
"If MDUpdateAction = New(0), for the first Market Data Entry in a message, either this field or a Symbol must be specified…"

In that case, what is the meaning of the message when MDUpdateAction=New(0) and the symbol is not specified and MDEntryRefID is specified? Would it hurt to specify the use of a unique MDEntryID (instead of MDEntryRefID) when MDUpdateAction = New(0)? (for book orders)

Opher Lekach
Optimark Technologies, Inc.

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[ original email was from Ryan Pierce - rpierce@taltrade.com ]
> As it stands, the description of the MDEntryRefID tag states that this item may be included in a message with MDUpdateAction=New(0).
>
> To quote from the draft standard:
> "If MDUpdateAction = New(0), for the first Market Data Entry in a message, either this field or a Symbol must be specified…"
>
> In that case, what is the meaning of the message when MDUpdateAction=New(0) and the symbol is not specified and MDEntryRefID is specified? Would it hurt to specify the use of a unique MDEntryID (instead of MDEntryRefID) when MDUpdateAction = New(0)? (for book orders)

As stated in FIX 4.2d2:

  • In cases where the identification of an instrument is long, the sender has the option of referring to a previous active Market Data Entry of the same instrument instead of duplicating the information.

This is the purpose of MDEntryRefID when MDUpdateAction=New(0). In cases of really long instrument definitions (i.e. derivatives) you can create a new entry that refers to a previous MDEntryID where a security is defined.