previous exposure can be occasionally difficult, although speakers of European Portuguese tend to understand Brazilian Portuguese better than vice versa, due to the heavy exposure to music, soap operas etc. from Brazil. Word ordering can be dramatically different between European and Brazilian Portuguese. Brazilian and European Portuguese currently have two distinct, albeit similar, spelling standards. A unified orthography for the two varieties (including a limited number of words with dual spelling) has been approved by the national legislatures of Brazil and Portugal and is now official; see Spelling reforms of Portuguese for additional details. Formal written standards remain grammatically close to each other, despite some minor syntactic differences. African Portuguese and Asian Portuguese are based on the standard European dialect, but have undergone their own phonetic and grammatical developments, sometimes reminiscent of the spoken Brazilian variant. A number of creoles of Portuguese have developed in African countries, for example in Guinea-Bissau and on the island of São Tomé. Serbo-Croatian Serbo-Croatian is a pluricentric language with four standards (Bosnian, Croatian, Montenegrin, and Serbian) promoted in Bosnia and Herzegovina, Croatia, Montenegro, and Serbia. These standards do differ slightly, but do not hinder mutual intelligibility. Rather, as all four standardised varieties are based on the prestige Shtokavian dialect, major differences in intelligibility are identified not on the basis of standardised varieties, but rather dialects, like Kajkavian and Chakavian. Lexical and grammatical differences between the ethnic variants are reportedly limited, even when compared with those between closely related Slavic languages (such as standard Czech and Slovak, Bulgarian and Macedonian). The Montenegrin standard is largely based on the Serbian, while Bosnian is a compromise between Croatian and Serbian ones; Croatian and Serbian standards show 95% mutual intelligibility. Shtokavian is largely mutually unintelligible with Kajkavian (which is closer to Slovene) and only partially intelligible with Chakavian. Spanish Spanish has both national and regional linguistic norms, which vary in terms of vocabulary, grammar, and pronunciation, but all varieties are mutually intelligible and the same orthographic rules are shared throughout. In Spain, Standard Spanish is based upon the speech of educated speakers from Madrid. All varieties spoken in the Iberian Peninsula are grouped as Peninsular Spanish. Canarian Spanish (spoken in the Canary Islands), along with Spanish spoken in the Americas (including Spanish spoken in the United States, Central American Spanish, Mexican Spanish, Andean Spanish, and Caribbean Spanish), are particularly related to Andalusian Spanish. The United States is now