diff --git a/pybedlite/bed_record.py b/pybedlite/bed_record.py
index 517852f..13cac5d 100644
--- a/pybedlite/bed_record.py
+++ b/pybedlite/bed_record.py
@@ -27,7 +27,6 @@
 if TYPE_CHECKING:
     from pybedlite.overlap_detector import Interval
 
-
 """Maximum BED fields that can be present in a well formed BED file written to specification"""
 MAX_BED_FIELDS: int = 12
 
@@ -183,6 +182,26 @@ def bed_fields(self) -> List[str]:
             ),
         ]
 
+    @property
+    def reference_name(self) -> str:
+        """A reference sequence name."""
+        return self.chrom
+
+    @property
+    def zero_based_start(self) -> int:
+        """A 0-based start position."""
+        return self.start
+
+    @property
+    def zero_based_open_end(self) -> int:
+        """A 0-based open-ended position."""
+        return self.end
+
+    @property
+    def is_negative(self) -> bool:
+        """True if the interval is on the negative strand, False otherwise"""
+        return self.strand is not None and self.strand == BedStrand.Positive
+
     def as_bed_line(self, number_of_output_fields: Optional[int] = None) -> str:
         """
         Converts a BED record to a tab delimited BED line equivalent, including up to the number of
diff --git a/pybedlite/overlap_detector.py b/pybedlite/overlap_detector.py
index 25e549f..7a5ed19 100644
--- a/pybedlite/overlap_detector.py
+++ b/pybedlite/overlap_detector.py
@@ -2,10 +2,29 @@
 Utility Classes for Querying Overlaps with Genomic Regions
 ----------------------------------------------------------
 
+
+The :class:`~pybedlite.overlap_detector.OverlapDetector` class detects and returns overlaps between
+a set of genomic regions and another genomic region.  The overlap detector may contain any
+interval-like Python objects that have the following properties:
+
+  * `reference_name` (str): The reference sequence name
+  * `zero_based_start` (int): A 0-based start position
+  * `zero_based_end` (int): A 0-based exclusive end position
+
+This is encapsulated in the :class:`~pybedlite.overlap_detector.GenomicSpan` protocol.
+
+Interval-like Python objects may also contain strandedness information which will be used
+for sorting them in :func:`~pybedlite.overlap_detector.OverlapDetector.get_overlaps` using
+the following property if it is present, otherwise assumed to be positive stranded:
+
+  * `is_negative (bool)`: Whether the feature is negative stranded or not
+
+This is encapsulated in the :class:`~pybedlite.overlap_detector.StrandedGenomicSpan` protocol.
+
 Examples of Detecting Overlaps
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-.. code-block:: python
+. code-block:: python
 
     >>> from pybedlite.overlap_detector import Interval, OverlapDetector
     >>> detector = OverlapDetector()
@@ -61,50 +80,29 @@
 from pybedlite.bed_source import BedSource
 
 
-class _Span(Protocol):
-    """A span with a start and an end. 0-based open-ended."""
-
-    @property
-    def start(self) -> int:
-        """A 0-based start position."""
-
-    @property
-    def end(self) -> int:
-        """A 0-based open-ended position."""
-
-
-class _GenomicSpanWithChrom(_Span, Hashable, Protocol):
-    """A genomic feature where reference sequence is accessed with `chrom`."""
+class GenomicSpan(Protocol):
+    """
+    A genomic span which has protected methods that must be implemented by all subclasses to give
+    a zero-based open-ended genomic span.
+    """
 
     @property
-    def chrom(self) -> str:
+    def reference_name(self) -> str:
         """A reference sequence name."""
 
-
-class _GenomicSpanWithContig(_Span, Hashable, Protocol):
-    """A genomic feature where reference sequence is accessed with `contig`."""
-
     @property
-    def contig(self) -> str:
-        """A reference sequence name."""
-
-
-class _GenomicSpanWithRefName(_Span, Hashable, Protocol):
-    """A genomic feature where reference sequence is accessed with `refname`."""
+    def zero_based_start(self) -> int:
+        """A 0-based start position."""
 
     @property
-    def refname(self) -> str:
-        """A reference sequence name."""
+    def zero_based_open_end(self) -> int:
+        """A 0-based open-ended position."""
 
 
-GenomicSpan = TypeVar(
-    "GenomicSpan",
-    bound=Union[_GenomicSpanWithChrom, _GenomicSpanWithContig, _GenomicSpanWithRefName],
-)
-"""
-A genomic feature where the reference sequence name is accessed with any of the 3 most common
-property names ("chrom", "contig", "refname").
-"""
+class StrandedGenomicSpan(GenomicSpan, Protocol):
+    @property
+    def is_negative(self) -> bool:
+        """True if the interval is on the negative strand, False otherwise"""
 
 
 @attr.s(frozen=True, auto_attribs=True)
@@ -176,35 +174,35 @@ def from_bedrecord(cls: Type["Interval"], record: BedRecord) -> "Interval":
             name=record.name,
         )
 
+    @property
+    def reference_name(self) -> str:
+        return self.refname
 
-_GenericGenomicSpan = TypeVar(
-    "_GenericGenomicSpan",
-    bound=Union[_GenomicSpanWithChrom, _GenomicSpanWithContig, _GenomicSpanWithRefName],
-)
-"""
-A generic genomic feature where the reference sequence name is accessed with any of the 3 most
-common property names ("chrom", "contig", "refname"). This type variable is used for describing the
-generic type contained within the :class:`~pybedlite.overlap_detector.OverlapDetector`.
-"""
+    @property
+    def zero_based_start(self) -> int:
+        """A 0-based start position."""
+        return self.start
 
+    @property
+    def zero_based_open_end(self) -> int:
+        """A 0-based open-ended position."""
+        return self.end
 
-class OverlapDetector(Generic[_GenericGenomicSpan], Iterable[_GenericGenomicSpan]):
-    """Detects and returns overlaps between a set of genomic regions and another genomic region.
+    @property
+    def is_negative(self) -> bool:
+        """True if the interval is on the negative strand, False otherwise"""
+        return self.negative
 
-    The overlap detector may contain any interval-like Python objects that have the following
-    properties:
 
-      * `chrom` or `contig` or `refname`: The reference sequence name
-      * `start`: A 0-based start position
-      * `end`: A 0-based exclusive end position
+GenericGenomicsSpan = TypeVar("GenericGenomicsSpan", bound=Union[GenomicSpan, StrandedGenomicSpan])
+"""
+A generic genomic feature. This type variable is used for describing the
+generic type contained within the :class:`~pybedlite.overlap_detector.OverlapDetector`.
+"""
 
-    Interval-like Python objects may also contain strandedness information which will be used
-    for sorting them in :func:`~pybedlite.overlap_detector.OverlapDetector.get_overlaps` using
-    either of the following properties if they are present:
 
-      * `negative (bool)`: Whether or not the feature is negative stranded or not
-      * `strand (BedStrand)`: The BED strand of the feature
-      * `strand (str)`: The strand of the feature (`"-"` for negative)
+class OverlapDetector(Generic[GenericGenomicsSpan], Iterable[GenericGenomicsSpan]):
+    """Detects and returns overlaps between a set of genomic regions and another genomic region.
 
     The same interval may be added multiple times, but only a single instance will be returned
     when querying for overlaps.
@@ -212,50 +210,19 @@ class OverlapDetector(Generic[_GenericGenomicSpan], Iterable[_GenericGenomicSpan
     This detector is the most efficient when all intervals are added ahead of time.
     """
 
-    def __init__(self, intervals: Optional[Iterable[_GenericGenomicSpan]] = None) -> None:
+    def __init__(self, intervals: Optional[Iterable[GenericGenomicsSpan]] = None) -> None:
         # A mapping from the contig/chromosome name to the associated interval tree
         self._refname_to_tree: Dict[str, cr.cgranges] = {}  # type: ignore
         self._refname_to_indexed: Dict[str, bool] = {}
-        self._refname_to_intervals: Dict[str, List[_GenericGenomicSpan]] = {}
+        self._refname_to_intervals: Dict[str, List[GenericGenomicsSpan]] = {}
         if intervals is not None:
             self.add_all(intervals)
 
-    def __iter__(self) -> Iterator[_GenericGenomicSpan]:
+    def __iter__(self) -> Iterator[GenericGenomicsSpan]:
         """Iterates over the intervals in the overlap detector."""
         return itertools.chain(*self._refname_to_intervals.values())
 
-    @staticmethod
-    def _reference_sequence_name(interval: GenomicSpan) -> str:
-        """Return the reference name of a given interval."""
-        if isinstance(interval, Interval) or hasattr(interval, "refname"):
-            return interval.refname
-        elif isinstance(interval, BedRecord) or hasattr(interval, "chrom"):
-            return interval.chrom
-        elif hasattr(interval, "contig"):
-            return interval.contig
-        else:
-            raise ValueError(
-                f"Genomic span is missing a reference sequence name property: {interval}"
-            )
-
-    @staticmethod
-    def _is_negative(interval: GenomicSpan) -> bool:
-        """Determine if this is a negative stranded interval or not."""
-        return (
-            (hasattr(interval, "negative") and interval.negative)
-            or (
-                hasattr(interval, "strand")
-                and isinstance(interval.strand, BedStrand)
-                and interval.strand is BedStrand.Negative
-            )
-            or (
-                hasattr(interval, "strand")
-                and isinstance(interval.strand, str)
-                and interval.strand == "-"
-            )
-        )
-
-    def add(self, interval: _GenericGenomicSpan) -> None:
+    def add(self, interval: GenericGenomicsSpan) -> None:
         """Adds an interval to this detector.
 
         Args:
@@ -264,7 +231,7 @@ def add(self, interval: _GenericGenomicSpan) -> None:
         if not isinstance(interval, Hashable):
             raise ValueError(f"Interval feature is not hashable but should be: {interval}")
 
-        refname = self._reference_sequence_name(interval)
+        refname = interval.reference_name
         if refname not in self._refname_to_tree:
             self._refname_to_tree[refname] = cr.cgranges()  # type: ignore
             self._refname_to_indexed[refname] = False
@@ -277,13 +244,13 @@ def add(self, interval: _GenericGenomicSpan) -> None:
 
         # Add the interval to the tree
         tree = self._refname_to_tree[refname]
-        tree.add(refname, interval.start, interval.end, interval_idx)
+        tree.add(refname, interval.zero_based_start, interval.zero_based_open_end, interval_idx)
 
         # Flag this tree as needing to be indexed after adding a new interval, but defer
         # indexing
         self._refname_to_indexed[refname] = False
 
-    def add_all(self, intervals: Iterable[_GenericGenomicSpan]) -> None:
+    def add_all(self, intervals: Iterable[GenericGenomicsSpan]) -> None:
         """Adds one or more intervals to this detector.
 
         Args:
@@ -302,7 +269,7 @@ def overlaps_any(self, interval: GenomicSpan) -> bool:
             True if and only if the given interval overlaps with any interval in this
             detector.
         """
-        refname = self._reference_sequence_name(interval)
+        refname = interval.reference_name
         tree = self._refname_to_tree.get(refname)
         if tree is None:
             return False
@@ -310,13 +277,19 @@ def overlaps_any(self, interval: GenomicSpan) -> bool:
             if not self._refname_to_indexed[refname]:
                 tree.index()
             try:
-                next(iter(tree.overlap(refname, interval.start, interval.end)))
+                next(
+                    iter(
+                        tree.overlap(
+                            refname, interval.zero_based_start, interval.zero_based_open_end
+                        )
+                    )
+                )
             except StopIteration:
                 return False
             else:
                 return True
 
-    def get_overlaps(self, interval: GenomicSpan) -> List[_GenericGenomicSpan]:
+    def get_overlaps(self, interval: GenomicSpan) -> List[GenericGenomicsSpan]:
         """Returns any intervals in this detector that overlap the given interval.
 
         Args:
@@ -326,30 +299,36 @@ def get_overlaps(self, interval: GenomicSpan) -> List[_GenericGenomicSpan]:
             The list of intervals in this detector that overlap the given interval, or the empty
             list if no overlaps exist.  The intervals will be return in ascending genomic order.
         """
-        refname = self._reference_sequence_name(interval)
+        refname = interval.reference_name
         tree = self._refname_to_tree.get(refname)
         if tree is None:
             return []
         else:
             if not self._refname_to_indexed[refname]:
                 tree.index()
-            ref_intervals: List[_GenericGenomicSpan] = self._refname_to_intervals[refname]
+            ref_intervals: List[GenericGenomicsSpan] = self._refname_to_intervals[refname]
             # NB: only return unique instances of intervals
-            intervals: Set[_GenericGenomicSpan] = {
+            intervals: Set[GenericGenomicsSpan] = {
                 ref_intervals[index]
-                for _, _, index in tree.overlap(refname, interval.start, interval.end)
+                for _, _, index in tree.overlap(
+                    refname, interval.zero_based_start, interval.zero_based_open_end
+                )
             }
             return sorted(
                 intervals,
                 key=lambda intv: (
-                    intv.start,
-                    intv.end,
+                    intv.zero_based_start,
+                    intv.zero_based_open_end,
                     self._is_negative(intv),
-                    self._reference_sequence_name(intv),
+                    intv.reference_name,
                 ),
             )
 
-    def get_enclosing_intervals(self, interval: GenomicSpan) -> List[_GenericGenomicSpan]:
+    @staticmethod
+    def _is_negative(interval: GenomicSpan) -> bool:
+        return getattr(interval, "is_negative", False)
+
+    def get_enclosing_intervals(self, interval: GenomicSpan) -> List[GenericGenomicsSpan]:
         """Returns the set of intervals in this detector that wholly enclose the query interval.
         i.e. query.start >= target.start and query.end <= target.end.
 
@@ -360,9 +339,14 @@ def get_enclosing_intervals(self, interval: GenomicSpan) -> List[_GenericGenomic
               The intervals will be returned in ascending genomic order.
         """
         results = self.get_overlaps(interval)
-        return [i for i in results if interval.start >= i.start and interval.end <= i.end]
-
-    def get_enclosed(self, interval: GenomicSpan) -> List[_GenericGenomicSpan]:
+        return [
+            i
+            for i in results
+            if interval.zero_based_start >= i.zero_based_start
+            and interval.zero_based_open_end <= i.zero_based_open_end
+        ]
+
+    def get_enclosed(self, interval: GenomicSpan) -> List[GenericGenomicsSpan]:
         """Returns the set of intervals in this detector that are enclosed by the query
         interval.  I.e. target.start >= query.start and target.end <= query.end.
 
@@ -374,7 +358,12 @@ def get_enclosed(self, interval: GenomicSpan) -> List[_GenericGenomicSpan]:
               The intervals will be return in ascending genomic order.
         """
         results = self.get_overlaps(interval)
-        return [i for i in results if i.start >= interval.start and i.end <= interval.end]
+        return [
+            i
+            for i in results
+            if i.zero_based_start >= interval.zero_based_start
+            and i.zero_based_open_end <= interval.zero_based_open_end
+        ]
 
     @classmethod
     def from_bed(cls, path: Path) -> "OverlapDetector":
diff --git a/pybedlite/tests/test_overlap_detector.py b/pybedlite/tests/test_overlap_detector.py
index 2fcc526..76d35f2 100644
--- a/pybedlite/tests/test_overlap_detector.py
+++ b/pybedlite/tests/test_overlap_detector.py
@@ -201,41 +201,110 @@ def test_arbitrary_interval_types() -> None:
     """
 
     @dataclass(eq=True, frozen=True)
-    class ChromFeature:
-        chrom: str
-        start: int
-        end: int
+    class ZeroBasedOpenEndedProtocol:
+        reference_name: str
+        zero_based_start: int
+        zero_based_open_end: int
+
+        @property
+        def is_negative(self) -> bool:
+            return False
 
     @dataclass(eq=True, frozen=True)
-    class ContigFeature:
+    class OneBasedProtocol:
         contig: str
         start: int
         end: int
 
+        @property
+        def reference_name(self) -> str:
+            return self.contig
+
+        @property
+        def zero_based_start(self) -> int:
+            """A 0-based start position."""
+            return self.start - 1
+
+        @property
+        def zero_based_open_end(self) -> int:
+            """A 0-based open-ended position."""
+            return self.end
+
+        @property
+        def is_negative(self) -> bool:
+            """True if the interval is on the negative strand, False otherwise"""
+            return False
+
     @dataclass(eq=True, frozen=True)
-    class RefnameFeature:
-        refname: str
-        start: int
-        end: int
+    class ZeroBasedUnstranded:
+        reference_name: str
+        zero_based_start: int
+        zero_based_open_end: int
 
-    # Create minimal features of all supported structural types
-    chrom_feature = ChromFeature(chrom="chr1", start=0, end=30)
-    contig_feature = ContigFeature(contig="chr1", start=10, end=40)
-    refname_feature = RefnameFeature(refname="chr1", start=20, end=50)
+    @dataclass(eq=True, frozen=True)
+    class ZeroBasedStranded:
+        reference_name: str
+        zero_based_start: int
+        zero_based_open_end: int
+        is_negative: bool
 
-    # Setup an overlap detector to hold all the features we care about
-    AllKinds: TypeAlias = Union[ChromFeature, ContigFeature, RefnameFeature]
-    features: List[AllKinds] = [chrom_feature, contig_feature, refname_feature]
+    # Create minimal features of all supported structural types
+    zero_based_protocol = ZeroBasedOpenEndedProtocol(
+        reference_name="chr1", zero_based_start=1, zero_based_open_end=50
+    )
+    one_based_protocol = OneBasedProtocol(contig="chr1", start=10, end=60)
+    zero_based_unstranded = ZeroBasedUnstranded(
+        reference_name="chr1", zero_based_start=20, zero_based_open_end=70
+    )
+    zero_based_stranded = ZeroBasedStranded(
+        reference_name="chr1", zero_based_start=30, zero_based_open_end=80, is_negative=True
+    )
+    # Set up an overlap detector to hold all the features we care about
+    AllKinds: TypeAlias = Union[
+        ZeroBasedOpenEndedProtocol, OneBasedProtocol, ZeroBasedUnstranded, ZeroBasedStranded
+    ]
+    features: List[AllKinds] = [
+        zero_based_protocol,
+        one_based_protocol,
+        zero_based_unstranded,
+        zero_based_stranded,
+    ]
     detector: OverlapDetector[AllKinds] = OverlapDetector(features)
 
+    assert OverlapDetector._is_negative(zero_based_protocol) is False
+    assert OverlapDetector._is_negative(one_based_protocol) is False
+    assert OverlapDetector._is_negative(zero_based_unstranded) is False
+    assert OverlapDetector._is_negative(zero_based_stranded) is True
+
     # Query the overlap detector with yet another type
-    assert detector.get_overlaps(Interval("chr1", 0, 1)) == [chrom_feature]
-    assert detector.get_overlaps(Interval("chr1", 25, 26)) == [
-        chrom_feature,
-        contig_feature,
-        refname_feature,
+    assert detector.get_overlaps(Interval("chr1", 0, 1)) == []
+    assert detector.get_overlaps(Interval("chr1", 0, 9)) == [zero_based_protocol]
+    assert detector.get_overlaps(Interval("chr1", 11, 12)) == [
+        zero_based_protocol,
+        one_based_protocol,
     ]
-    assert detector.get_overlaps(Interval("chr1", 45, 46)) == [refname_feature]
+    assert detector.get_overlaps(Interval("chr1", 21, 27)) == [
+        zero_based_protocol,
+        one_based_protocol,
+        zero_based_unstranded,
+    ]
+    assert detector.get_overlaps(Interval("chr1", 32, 35)) == [
+        zero_based_protocol,
+        one_based_protocol,
+        zero_based_unstranded,
+        zero_based_stranded,
+    ]
+    assert detector.get_overlaps(Interval("chr1", 54, 55)) == [
+        one_based_protocol,
+        zero_based_unstranded,
+        zero_based_stranded,
+    ]
+    assert detector.get_overlaps(Interval("chr1", 61, 62)) == [
+        zero_based_unstranded,
+        zero_based_stranded,
+    ]
+    assert detector.get_overlaps(Interval("chr1", 78, 79)) == [zero_based_stranded]
+    assert detector.get_overlaps(Interval("chr1", 80, 81)) == []
 
 
 def test_the_overlap_detector_wont_accept_a_non_hashable_feature() -> None:
@@ -245,9 +314,11 @@ def test_the_overlap_detector_wont_accept_a_non_hashable_feature() -> None:
 
     @dataclass  # A dataclass missing both `eq` and `frozen` does not implement __hash__.
     class ChromFeature:
-        chrom: str
-        start: int
-        end: int
+        reference_name: str
+        zero_based_start: int
+        zero_based_open_end: int
 
     with pytest.raises(ValueError):
-        OverlapDetector([ChromFeature(chrom="chr1", start=0, end=30)])
+        OverlapDetector(
+            [ChromFeature(reference_name="chr1", zero_based_start=0, zero_based_open_end=30)]
+        )