Starting price (SP)
The starting price is the official odds of a horse or greyhound at the off, used to settle bets without a taken price and central to best odds guaranteed (BOG).
A punter who asks for SP does not know the price when the bet goes on. The bet settles at whatever is returned for that runner as the race starts, which can be bigger or smaller than the prices offered earlier in the day. The alternative is a fixed price, often called the early or board price, locked in when the bet is struck.
Prices move before the off. A runner whose price lengthens is said to drift, and one whose price shortens is said to be backed in. A punter who took a fixed price on a drifter would have done better at SP, and one who took it on a runner backed in did better with the fixed price.
Best odds guaranteed joins the two. Take a fixed 6.0 for 10 units, and if the SP comes back at 8.0 a BOG bookmaker pays 70 units profit where the fixed price paid 50. If the SP is 5.0, the fixed 6.0 stands and pays 50.
For matched bettors the SP is upside they cannot plan on. The qualifying loss is fixed once the back bet at the fixed price and the exchange lay are on, and a bigger SP adds to the back bet's return only if the horse wins. A tool therefore works from the fixed price alone.
Two details catch people out. A bet struck at SP gains nothing from BOG, since there is no fixed price to compare it with. An each-way bet struck at SP settles its place part at the place fraction of the SP. Both are set out in each bookmaker's terms.
In the OddsRelay feed
The feed carries no SP field. Its racing prices are pre-match, so on GET /v2/odds/bog each outcome has back[].price, the fixed price each bookmaker is offering, beside lay[].price and lay[].available from the exchanges, and meta.processed_at gives the response's time. The SP arrives after the off, and the BOG uplift is paid by the bookmaker from its own settlement, outside the data.
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