# What to do with map to file **URL:** \ **Category:** system-implementation\ **Created:** [March 8, 2017, 11:20am UTC](https://forum.loinc.org/t/what-to-do-with-map-to-file/934 "2017-03-08T11:20:39Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![jeroenfarmedvisie](https://forum.loinc.org/letter_avatar_proxy/v4/letter/j/e495f1/32.png) [@jeroenfarmedvisie](https://forum.loinc.org/u/jeroenfarmedvisie)\ **Post date:** [March 8, 2017, 11:20am UTC](https://forum.loinc.org/t/what-to-do-with-map-to-file/934/1 "2017-03-08T11:20:39Z")
We are implementing LOINC code in our application. Can someone tell me what to do with the map to table? Is this table to find a LOINC code wich is not in the LOINC table? ---
**Author:** ![jeroenfarmedvisie](https://forum.loinc.org/letter_avatar_proxy/v4/letter/j/e495f1/32.png) [@jeroenfarmedvisie](https://forum.loinc.org/u/jeroenfarmedvisie)\ **Post date:** [March 13, 2017, 7:20am UTC](https://forum.loinc.org/t/what-to-do-with-map-to-file/934/2 "2017-03-13T07:20:39Z")
I checked all the loinc numbers in the map\_to file. There 2810 records. If I check the all the values in the first column LOINC against the LOINC table I get a match of 2355. If I match the second column MAP\_to against the LOINC table I get 2377 matches. I expect a full match on the second colum. Is there someone who can explain why there is not a full match or what is the use of this file? ---
**Author:** ![jhook](https://forum.loinc.org/letter_avatar_proxy/v4/letter/j/aca169/32.png) [@jhook](https://forum.loinc.org/u/jhook)\ **Post date:** [March 14, 2017, 8:26am UTC](https://forum.loinc.org/t/what-to-do-with-map-to-file/934/3 "2017-03-14T08:26:51Z")
The MAP\_TO table is used to identify the appropriate replacement for LOINC terms that have been DEPRECATED or DISCOURAGED. You can find a detailed explanation in section 11.2 of the [LOINC Users’ Guide](https://loinc.org/downloads/resolveuid/5b10b078cb8a73852124468027bc9808 "LOINC Users' Guide"). I have examined the MAP\_TO table distributed in the 2.59 release of LOINC. I can find no LOINC number in the MAP\_TO.LOINC or MAP\_TO.MAP\_TO column that does not also appear in the LOINC.LOINC column. Can you please provide examples of the LOINC numbers that you cannot find? Regards, John ---
**Author:** ![system](https://forum.loinc.org/uploads/default/original/1X/dbab97ce9b2987d788a376e254fcaae249f3b672.png) [@system](https://forum.loinc.org/u/system)\ **Post date:** [June 23, 2023, 3:36pm UTC](https://forum.loinc.org/t/what-to-do-with-map-to-file/934/4 "2023-06-23T15:36:37Z")