Here's a description by Tom Bierovic. Given the probs with volume measurement in forex, this might be very useful tool. Can someone make it?

On Balance True Range by Thomas A. Bierovic

On-Balance True Range (OBTR) is my attempt to improve on the old On-Balance Volume study (OBV). In OBV you add today's volume to a running total of volume if the market closes higher than yesterday, and you subtract today's volume from a running total of volume if the market closes lower than yesterday. The OBV line confirms the current trend by making new highs or new lows along with prices, or it warns of a possible trend reversal by diverging from price action.

Since there is a high statistical correlation between volume and True Range, I simply substitute True Range for volume in the OBV study. True Range is usually just the difference between a period's high and low. However, if the previous close is below the current period's low, True Range is the difference between the current high and the previous close. If the previous close is above the current high, True Range is the difference between the previous close and the current low. In other words, True Range fills in the gaps. On-Balance True Range is an improvement to On-Balance Volume because you donŐt have to rely on tick volume or wait until tomorrow to obtain actual volume figures and because OBTR more accurately reflects a market's real activity when there is a gap.

To calculate OBTR, just add the current period's True Range to a runningtotal of True Ranges if the market closes higher than the previous period'sclose or subtract the current period's True Range from a running total ofTrue Ranges if the market closes lower than the previous period's close.