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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

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 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 235

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 -URI http://asc.fasb.org/extlink&amp;oid=26873400&amp;loc=d3e23780-122690



Reference 2: http://www.xbrl.org/2003/role/presentationRef

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 -Article 4



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 -Publisher SEC

 -Name Regulation S-X (SX)

 -Number 210

 -Article 12

 -Section 13

 -Sentence Column A



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</LabelSeparator><Level>4</Level><ElementName>opxa_WarrantRedemptionPriceDescription</ElementName><ElementPrefix>opxa_</ElementPrefix><IsBaseElement>false</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>terseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell><Cell FlagID="0" ContextID="eol_PE10315---1310-Q0011_STD_23_20130123_0" UnitID=""><Id>2</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>Opexa can redeem the warrants at $0.01 per  share if the Company's common stock closes at or above $10.00 per share for 20  consecutive trading days.</NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell><Cell FlagID="0" ContextID="eol_PE10315---1310-Q0011_STD_29_20130129_0" UnitID=""><Id>3</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>The  warrants at $0.01 per underlying share of common stock if the common stock  closes at or above $10.00 per share for 20 consecutive trading days.</NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell><Cell FlagID="0" ContextID="" UnitID=""><Id>4</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell><Cell FlagID="0" ContextID="" UnitID=""><Id>5</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell><Cell FlagID="0" ContextID="" UnitID=""><Id>6</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><ElementDefenition>Warrant Redemption Price, Description</ElementDefenition><ElementReferences>No definition available.</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Terms for warrant redeem</Label></Row><Row FlagID="0"><Id>13</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 235

 -SubTopic 10

 -Section S99

 -Paragraph 1

 -Subparagraph (SX 210.4-08.(i)(2))

 -URI http://asc.fasb.org/extlink&amp;oid=26873400&amp;loc=d3e23780-122690



Reference 2: http://www.xbrl.org/2003/role/presentationRef

 -Publisher SEC

 -Name Regulation S-X (SX)

 -Number 210

 -Section 08

 -Paragraph i

 -Subparagraph 2

 -Article 4



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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (f)(2)(iv)

 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (c)(1)(iv)(3)

 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (c)(1)(iv)(1)

 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (a)(1)

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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (c)(1)(iv)(1)

 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (f)(2)(iii)

 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (c)(1)(iv)(1)

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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (a)(1)

 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (a)(1)

 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (a)(3)

 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



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 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



Reference 2: http://www.xbrl.org/2003/role/presentationRef

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 -Name Accounting Standards Codification

 -Topic 718

 -SubTopic 10

 -Section 50

 -Paragraph 2

 -Subparagraph (c)(1)(i)-(ii)

 -URI http://asc.fasb.org/extlink&amp;oid=6415400&amp;loc=d3e5070-113901



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