Money appropriated for one purpose cannot be used for a different purpose, according to the Purpose Act (). The annual DoD appropriations acts include approximately 100 different appropriations (known as "colors of money"), and by this rule operations and maintenance (O&M) funds may not be used to buy weapons. Even an expenditure within the apparent scope of one appropriation may not be permissible if there is a more specific appropriation or the agency has made a previous funds election contrary to the proposed use of funds. For example, O&M fund can be used for purchasing repair parts, but if the parts are required to effect a major service life extension that is no longer repair but replacement – procurement funds must be used if the total cost is more than $250,000 (otherwise known as the Other Procurement threshold, for example, Other Procurement Army (OPA) threshold) or another procurement appropriation is available such as the armored vehicle or weapons appropriation.