Shulchan Arukh, Orach Chayyim 3:13:
לא ישתין מעומד, מפני ניצוצות הניתזין על רגליו, אם לא שיעמוד במקום גבוה, או שישתין לתוך עפר תחוח פירוש, קרקע שאינה בתולה, אלא כגון של ארץ חרושה).
One should not urinate from a standing position lest it sprinkle down upon his legs, if he is not on a high place, or relieving himself upon loose earth (meaning, soil that is not virgin, but rather like plowed earth).
If one is not allowed to urinate in a standing position, then how are men allowed to use urinals?
Second question related to urinals:
Shulchan Arukh, Orach Chayyim 3:2:
יהא צנוע בבית הכסא, ולא יגלה עצמו עד שישב
One should be modest in the bathroom stall, and not reveal oneself until sitting.
The above law seems to focus on sitting (defecating), but, it does imply a general rule of modesty in the bathroom, whether you reveal yourself standing or sitting. If so, isn't using a urinal a lack of modesty, esp. in those places where there is one large urinal (like a "trough") against the wall, and multiple men urinate in it (i.e. - there is no partition. These large urinals seem to be common at baseball stadiums.) Are you allowed to use such a urinal, if this may be a lack of modesty?