CSV formats are best used to represent sets or sequences of records in which each record has an identical list of fields. This corresponds to a single relation in a relational database, or to data (though not calculations) in a typical spreadsheet. The format dates back to the early days of business computing and is widely used to pass data between computers with different internal word sizes, data formatting needs, and so forth. For this reason, CSV files are common on all computer platforms. CSV is a delimited text file that uses a comma to separate values (many implementations of CSV import/export tools allow other separators to be used; for example, the use of a "Sep=^" row as the first row in the *.csv file will cause Excel to open the file expecting caret "^" to be the separator instead of comma ","). Simple CSV implementations may prohibit field values that contain a comma or other special characters such as newlines. More sophisticated CSV implementations permit them, often by requiring " (double quote) characters around values that contain reserved characters (such as commas, double quotes, or less commonly, newlines). Embedded double quote characters may then be represented by a pair of consecutive double quotes, or by prefixing a double quote with an escape character such as a backslash (for example in Sybase Central). CSV formats are not limited to a particular character set. They work just as well with Unicode character sets (such as UTF-8 or UTF-16) as with ASCII (although particular programs that support CSV may have their own limitations). CSV files normally will even survive naive translation from one character set to another (unlike nearly all proprietary data formats). CSV does not, however, provide any way to indicate what character set is in use, so that must be communicated separately, or determined at the receiving end (if possible). Databases that include multiple relations cannot be exported as a single CSV file. Similarly, CSV cannot naturally represent hierarchical or object-oriented data. This is because every CSV record is expected to have the same structure. CSV is therefore rarely appropriate for documents created with HTML, XML, or other markup or word-processing technologies. Statistical databases in various fields often have a generally relation-like structure, but with some repeatable groups of fields. For example, health databases such as the Demographic and Health Survey typically repeat some questions for each child of a given parent (perhaps up to a fixed maximum number of children). Statistical analysis systems often include utilities that can "rotate" such data; for example, a "parent" record that includes information about five children can be split into five separate records, each containing (a) the information on one child, and (b) a copy of all the non-child-specific information.