Attaching Search Helps to Screen Fields 
A search help is used to influence the behavior of a field when the input help is called. The search help must be assigned to the field in order to do this. You can:
Hierarchy of the Search Help Call
Due to the different options for search help attachments, more than one search help can be assigned to one field.

A search help A is assigned directly to a field in the screen. Search help B is attached to the corresponding table field. There is a check table that is assigned a further search help C for the field. There is another search help D attached to the data element of the field.
Such conflicts can be solved by defining a hierarchy for the assigned search helps.
The search help attached to the screen field is first displayed. If there is no such field, the search help of the table field is called. If there is no search help here either, the input help of the check table is used (if a foreign key is defined). Two cases must be distinguished here. If the check table has a search help, it is displayed. Otherwise only the key values of the check table are displayed. If there is a
text table for the check table, the texts are included in the logon language. If there is no check table, the search help is called from the data element.The following graphic shows the hierarchy of the search help call. Read the graphic from the top downward and from left to right. Search help attachment A has priority over search help attachment B if A is above B or if A and B are at the same level and A is further left.
The search help attachments for the screen therefore have the highest priority. The search help attachments for the ABAP Dictionary are next in priority.