摘要 |
A file creation method comprising:creating file content at a particular location and time using a portable device; and obtaining data from wireless communication devices detectable by the portable device at the particular location and time thereby to obtain a set of data. The set of data identifies or enables identification of the wireless communication devices. The method further comprises associating the set of data and time with the file content to enable subsequent analysis to determine the particular location using a time-dependent database. |