In WHO 'Road to health card' the upper reference line represents:

50th percentile for boys. The Indian growth cha is having 4 reference curves. The topmost curve corresponds to 80 % of the median of the WHO reference standard. The lower lines represent 70 %, 60 %, 50 % of that standard. WHO growth cha is having 2 reference curves. The upper reference curve represent the median (50'" percentile) for boys and the lower reference curve the 3'" percentile for girls. The space between the two growth curves is called as road to health. This will include the zone of normality.