The latest bark restrictions that countries around the world have or are in various stages of adopting under the ISPM-15 Standard are simply described as follows.
Your Wood Packaging Material (WPM) – crates, pallets, dunnage do not need to be 100% bark-free – the limits of how much bark can be on each component (that's key – not on the entire assembly; this refers to the allowable amount of bark on each particular component/piece) are described with two statements:
1) Less than 3 cm (yes that's metric for 1.18 inches) in width, regardless of length – so you can have a piece of lumber on your crate or pallet that's 120 feet long and has a strip of bark that's up to but not over 1.18" wide and running the entire length of the component and you are within the boundaries of the ISPM-standard.
2) If the bark on your component (again it's by piece/component – not the entire crate or pallet or assembly) is greater than 3 cm in width (1.18 inches), the total surface area of an individual piece of bark must be less than 50 square centimeters (there's the metric system again – 7.75 square inches) or roughly the size of a credit card. To calculate the area of bark simply multiply the length by the width and there you have the square centimeters (area).
There are tools supplied by various organizations involved with the lumber and inspection industries that can make this an easy task for persons within your organization that work with your organization's pallets, crates, or dunnage meant for export. You can find them by doing an online search for the "bark measurement tool."
While I have your attention, other important questions that usually come up related to the subject of export restrictions on WPM are sampled here – but please don't hesitate to contact me directly if I can be of further help.