android - Why doesn't the subtype of this custom MIME type specify the particular row (from Content URI) in the table? -

at end of the developer guide, have described vnd.android.cursor.dir type part of every custom mime type, multiple rows; , vnd.android.cursor.item single row.

then there example of content provider contains train timetables. it's authority com.example.trains , has tables line1, line2, , line3. , it's content uri

content://com.example.trains/line2/5 

which pointing "5th row in line2 table", mime type returned be:

vnd.android.cursor.item/vnd.example.line2 

which not indicate row is.

questions:

1. i think should be like:

   vnd.android.cursor.item/vnd.example.line2.5 

   because type part describe mime type particular row, subtype should describe row is. isn't it?

2. if vnd.android.cursor.item/vnd.example.line2 correct, means not matter if mime type of particular row. does mean rows in table have same mime type? because mime type type of files on internet. (reference) think since rows have same "types" of data (or in other words rows in table kinda instances of same thing) - think rows in table should inherently have same mime type?

3. if ^ yes, then point of having categorization vnd.android.cursor.dir , vnd.android.cursor.item ?

i think should like:

vnd.android.cursor.item/vnd.example.line2.5

because type part describe mime type particular row, subtype should describe row is. isn't it?

no, no more mime type web page text/html.30821182 because happens question #30821182 on web site. mime types in android represent data formats.

does mean rows in table have same mime type?

in provider, yes.

because mime type type of files on internet.

android stretches definition of mime type more generic files. in case of database-style api of contentprovider, mime type there link data structure uri activity can work data structure.

i think rows in table should inherently have same mime type?

that typical pattern database-style contentprovider api.

then point of having categorization vnd.android.cursor.dir , vnd.android.cursor.item ?

the former represents collection of content, think of table or view in sql database. latter represents instance of content, think of row in table or view in sql database.