Execution Instruction : Percentage of Volume

Imported from previous forum

On Order Single, if you select an Execution Instruction of "D" (Percent of Volume) where should you put the Percentage required?
I imagine that this is used for an instruction of 1/3rd of the volume, in which case how is this expressed?

[ original email was from Ryan Pierce - rpierce@taltrade.com ]
> On Order Single, if you select an Execution Instruction of "D" (Percent of Volume) where should you put the Percentage required?
> I imagine that this is used for an instruction of 1/3rd of the volume, in which case how is this expressed?

My understanding is that this instruction means that the order should account for a percent of the volume on the exchange floor, and not be the only order out there on the floor. A specific percent is not specified.