Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Troubleshooting; Situational Awareness; Communication Breakdown; Confusion
Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Taxiway
Flight Crew Became Reoriented
Environment - Non Weather Related
We departed the gate and were instructed to taxi to Runway 28 via 'D; A; A1 to the Runway 28 holding point.'  Upon glancing at the taxi diagram; referencing the our Airway Manual (AM); to verify our taxi route; I quickly realized a discrepancy between the instructions we were given and the chart -- there was no A1 taxiway that reached the runway.  Before we could inquire about these instructions; the controller gave us a 'follow the aircraft ahead' instruction.  Digging a little farther; I began to notice that this discrepancy was worth a report submittal because the 10-9 Chart for MMGL differs from the AM; and neither the 10-9 Chart nor the AM agrees with the airport in reality.  Upon your own review; you will discover that there is a difference in taxiway names between the 10-9 chart; and the AM; specifically as it relates to the A taxiway.  Additionally; in reality there is an A1 taxiway; properly signed; that parallels the A taxiway toward the approach end of Runway 28.  There is also an additional taxiway; A2; that connects the A taxiway to the runway; prior to the approach end of Runway 28 which is not charted on either chart. The airport NOTAMS reference a change in taxiway naming convention; however; the NOTAMS do not make sense with either the current charts; or with reality; and in fact lead to more confusion.  I believe that by paying attention to aircraft position with reference to the published chart; I was able to help the Captain remain in the green; and hopefully trap this threat from snaring other crews.  In deliberating whether to submit this report; I concluded that since this threat affects the broader aviation community; the report would be more appropriate for resolving this discrepancy to the benefit of everyone.
Air Carrier First Officer reported confusion regarding the taxi instructions from MMGL ground control and the taxi chart.