Solution : https://service.sap.com/sap/support/notes/729348 (SAP Service marketplace login required)
Key words :
-digit language-dependent external, relevant uppercase letters directly, sap proposal pool, attached z_ossnote_729348 report, t006a-mseh3 field, lower case 'µ', standard sap system, error message bm305, capital letter 'm', relevant language
Related Notes :
| 1319517 | Unicode Collection Note |
| 1171718 | Problems with lowercase letters for measurement units |
| 853569 | Problems with allowed characters in 0UNIT (for example µ) |
| 789748 | No lowercase letters for unit of measurement IDs |