and as such, there are often tighter restrictions placed around advertisements for food and healthcare products. The advertising industries within some countries rely less on laws and more on systems of self-regulation. Advertisers and the media agree on a code of advertising standards that they attempt to uphold. The general aim of such codes is to ensure that any advertising is 'legal, decent, honest and truthful'. Some self-regulatory organizations are funded by the industry, but remain independent, with the intent of upholding the standards or codes like the Advertising Standards Authority in the UK. In the UK, most forms of outdoor advertising such as the display of billboards is regulated by the UK Town and County Planning system. Currently, the display of an advertisement without consent from the Planning Authority is a criminal offense liable to a fine of £2,500 per offense. In the US, many communities believe that many forms of outdoor advertising blight the public realm. As long ago as the 1960s in the US, there were attempts to ban billboard advertising in the open countryside. Cities such as São Paulo have introduced an outright ban with London also having specific legislation to control unlawful displays. Some governments restrict the languages that can be used in advertisements, but advertisers may employ tricks to try avoiding them. In France for instance, advertisers sometimes print English words in bold and French translations in fine print to deal with Article 120 of the 1994 Toubon Law limiting the use of English. The advertising of pricing information is another topic of concern for governments. In the United States for instance, it is common for businesses to only mention the existence and amount of applicable taxes at a later stage of a transaction. In Canada and New Zealand, taxes can be listed as separate items, as long as they are quoted up-front. In most other countries, the advertised price must include all applicable taxes, enabling customers to easily know how much it will cost them. Theory Hierarchy-of-effects models Various competing models of hierarchies of effects attempt to provide a theoretical underpinning to advertising practice. The model of Clow and Baack clarifies the objectives of an advertising campaign and for each individual advertisement. The model postulates six steps a buyer moves through when making a purchase: Awareness Knowledge Liking Preference Conviction Purchase Means-end theory suggests that an advertisement should contain a message or means