Problems with Oracle conversion time: Ora-01810:format code appears twice

The To_date () function in Oralce is used to convert a string to a Date object:

To_date (String,  [  format_mask  ] ,  [  Nls_language   ]  

string1 the string to convert.

format_mask option, date conversion format.

nls_language options available. Specifies the NLS language used to convert strings.

Problem

Ora-01810:format Code appears twice
You might specify a date format like Java, such as:
To_date (' 2006-06-01 18:00:00 ' yyyy-mm-dd hh:MM:ss ')
The date format in Oracle is case insensitive, so mm appears two times.
The correct wording is:
To_date (' 2006-06-01 18:00:00 ' yyyy-mm-dd hh:mi:ss ')

HH--Hour of Day (1-12).
HH12--Hour of Day (1-12).
HH24--Hour of Day (0-23).
MI--Minute (0-59).
SS--Second (0-59).

The summary is that Oracle is sentimental ~