According to the official standards set by the People’s Republic of China, standard Mandarin Chinese uses:
The phonology or sound system of Beijing.
There’s a distinction between the sound system of a dialect or language. It differs from the actual pronunciation of words within it.
The pronunciations of words chosen for standard Mandarin Chinese do not necessarily reproduce those of the Beijing dialect.
The pronunciation of words depends on the standardization and occasional standardization differences (not accents) do exist, between putonghua and guoyu.
For example, in fluent speech, Chinese speakers can easily distinguish between the Beijing dialect and standard Mandarin Chinese.
Beijingers speak standard Mandarin Chinese with elements of their own dialect in the same way as other speakers.
The vocabulary of Mandarin Chinese dialects, in general, excludes all slang and other elements deemed “regionalisms”.
In addition, the vocabulary of all Chinese dialects, especially in more technical fields like science, law, and government, are very similar. (This is similar to the profusion of Latin and Greek words in European languages.) This implies that standardized Mandarin Chinese shares much of its vocabulary with all varieties of Chinese.
In other words, standard Mandarin Chinese does not include slang and many colloquial words from the Beijing dialect, making them potentially incomprehensible to people outside Beijing.
Exemplary modern Chinese literature, like the works of Lu Xun, collectively contributes to the grammar and diction known as “Vernacular Chinese”.
Vernacular Chinese, the standard written form of modern Chinese, is in turn based loosely upon a mixture of northern (predominant), southern, and classical grammar and diction.
This gives formal standard Mandarin Chinese a slightly different feel from that of the common Beijing dialect.
In comparing standard Mandarin Chinese with the Beijing dialect, note the difference in the word for ‘door.’ Standard Mandarin pronounces it as ‘men,’ while the Beijing dialect uses ‘menr.’
In theory, the People’s Republic of China defines standard Mandarin Chinese differently. However, in reality, the differences are minor and primarily concentrated in the tones of a small minority of words.
Although Chinese speakers make a clear distinction between standard Mandarin Chinese and the Beijing dialect, there are aspects of the Beijing dialect that have made it into the official standard.
Standard Mandarin Chinese has a distinction between the polite and informal versions of “you” that comes from the Beijing dialect.
In addition, there is a distinction between “zánmen” (we including the listener) and “wŏmen” (we not including the listener). In practice, neither distinction is commonly used by most Chinese.