Entering dates: Show month number in addition to or in place of abbrevation

Entering dates on a touchscreen device is more tricky than entering other types of fields, and the entry error rates are unacceptably high, as measured in a recent experiment entering more than 10,000 known dates in 12 different combinations of factors (phone vs. tablet; single-entry vs double-entry; calendar vs. no-calendar vs. radio button interface). (Mean rate = 1 error in every 20 dates, after throwing out data from 5 persons (of 24) with worst performance; the rate varied by combination of factors and was worst for the ODK default calendar interface on a smart phone, single-entry, averaging one error in every 10 dates entered.)

In some contexts, field staff are copying dates from a written record and it would be helpful to be able to format the interface to look as much like the written dates as possible. Rather than list only an abbreviation for month, it would be helpful to add the month number so both are listed (e.g., 01 Jan).

No files, tests, or entry points are identified in the issue. Start by locating the date-entry calendar interface and its month-label formatting; done means the interface can show the month number alongside or instead of the abbreviation, including the requested written-date style.

Written by the indexing model from the issue text.