boards may be added. These boards are often called cleats. A cleat is used to provide support to a panel when that panel has reached a size that may require added support based on the method of transportation. Cleats may be placed anywhere between the edges of a given panel. On crates, cleat placement is often determined by the width of the plywood used on plywood sheathed crates. On other crates, cleats are often evenly spaced as required to strengthen the panel. Sometimes two cleats are added across the top panel of a crate placed as needed to give the top of the crate added strength where lifting chains or straps may press on the crate while lifting. When the dimensions of a crate side necessitate more than one piece of plywood be used in that crate side's construction, additional boards called 'battens' are used to cover and provide support to the seams between abutting pieces of plywood. Battens are typically wider than cleats, but do not need to be so. Cleats may have more specific names based on added benefit they provide. Some published standards only use those more descriptive terms and may never refer to these various lumber components as cleats. For example, lumber placed under the top of a wood container to add support for a large top are called "joists". Lumber is built into the midsection of the top of a wood container to strengthen the top are called "cleats". When the cleats are enlarged and constructed to support a large top, they may generically be termed "cleats" or more specifically be termed "joists". "Skids" or thick bottom runners, are sometimes specified to allow forklift trucks access for lifting. Transportation methods and storage conditions must always be considered when designing a crate. Every step of the transportation chain will result in different stresses from shock and vibration. Differences in pressure, temperature and humidity may not only adversely affect the content of the crate, but also will have an effect on the holding strength of the fasteners (mostly the nails and staples) in the crate. In some countries, any wooden crate being designed to ship overseas must be treated to ISPM 15 standards or commonly known as the “bug stamp” to prevent the spread of disease and insects. Although the above definition almost always stands true, there are many slightly altered or 'sub-definitions' used by and in