What is important, when an ascii-import of datapoints should be done?

There are a lot of system and runtime informations which are stored onto internal datapoints. All these datapoints start with "_", e.g. "_AcStructure". When importing a datapoint list, you have to be sure, that no internal datapoints are overwritten unintended.
In general, import only project specific datapoints named without leading "_" (e.g. Motor01, R1_990JW1101_PUMP_FL )

Under some circumstances it is necessary to import internal datapoints too (e.g. power configs and dynamic attributes for mass parametrization). In this case be sure, that your import files include only the corresponding internal datapoints. When you are exporting a datapoint list with WinCC OA Version 3.10 you can select “Power Config Settings” in addition to the selected datapoints to get these attributes into your ascii file.

Make a copy of the actual stock of all internal datapoints:
Define a datapoint filter like “_**” at the Ascii Manager Panel, select all filter items except historical parametrization and start an export.
This ascii file can be re-imported in case something went wrong with your project import.