Hello,

Weight for length (WLZ) is intended for children under 2, who cannot stand, so the word "Length" is used in this case. There is a difference between length and height. If you take measurements for the same child, lying down (length) and standing (height), you would find a difference in measurements, cause the relaxed body of the child during length measurement will probably be higher the standing one.
This is why you have two tables for length/height and you should use that according to the age (<2) or by using 87 cm wooden stick if you don't know the age. Some older children above two refuse to stand or they may have medical conditions prevent them from standing, so you take their length and add 0.7 cm to when you check the weight for height (WHZ )table.

The chart that starts with 45 cm is basically for <6 months infants if you have a TFC centre and you include <6 months you will need it. Otherwise, use the 6-23 mo and 24-59 mo charts for boys and girls. Please refer to your country's protocol as there are some minor variations in measurement protocols across countries.

The charts can be downloaded from the WHO website:
http://www.who.int/childgrowth/standards/en/

I hope that helps,

Regards,

Sameh

small correction: subtract 0.7 cm on WHZ.Thanks.