I am in agreement with [MENTION=206446]tauphi[/MENTION] on this. An S1 visa is granted for those visiting (or accompanying as a dependent) and expected to be in China greater than 180 days. But in the first 30 days after arrival on S1 status, the visa is converted to a Residence Permit (length of the RP granted varies depending on the situation and passport country). At that point, the S1 is voided in the system and the RP becomes the legal vehicle by which the foreigner exists in China as well as exits and re-enters. Many people persist in saying they are on S1 status but in the strictest technical sense, that is only the initial entry vehicle to get into China. What does carry over from visa to RP are the terms: in other words, an S1 is for family visits, and you cannot come to China on this and expect to take on employment that you might find while in China. It is safe to assume that the Chinese Immigration/police database does keep track of the initial visa granted (Z1 for employment, X1 for study, S1 for family, Q1 for Chinese family) even if all of these types of longer visas get converted to RP's. And that while on RP, you better be doing the activity that your original visa was granted for.

Registering your place of residence with the local police is a completely different and separate requirement that exists for everybody, regardless of visa (or RP status).